DLTK difficulties based on my opinion from my initial playthrough:
Cartel 3/10
Bodega 4/10
Miami 1.5/10
Shipyard 2.5/10
China 8/10
Club 1/10
Grounds 1/10
Airport 3.5/10
Alps 9.5/10
Foundry 1.5/10
Forest 2/10
Capture 0.5/10
Prison 5.5/10
Ranch 1/10
Hideout 6/10
Knox 7/10
Vaults 4/10
Plane 5.5/10
Crab Key 5.5/10
Island 5/10

Cartel A: Good
Cartel SA: new start lure, lure the gate guard by shooting as you get near him rather than going into his little hut, use a slap strat for better B leaves
Cartel 00A: same as above + Buyer List stuff; route inside building is nearest staircase, forward->left to office, get list, and head out through the other side, and then out
Cartel DLTK: should be easyish, but would require lots of luring, grab the BA early on and use the explosives to kill, camp on one of the silos and pick off all the patrolling guards, then slowly pick away at all guards along the streets, let them approach at first so that hitting them doesn't lure additional guards, slowly pick off the rest, nothing fancy, and for the building with the list, you can circle around the little pool near the office to abuse AI

Bodega A/SA: Good, but should be charging speed on the leave for Capungo. Stop earlier, then charge on SA.
Bodega 00A: basically like SA but need to kill off all the Civs, should be simple routing
Bodega DLTK: can kill rooftop guards and guards around the bottom for ammo, lure a bunch of basement guards to a nearby explosive, then boom them, such as the suite closest to the roof. 2 BAs are helpful. For cellar, can use frozen guard glitch, or pick them off slowly like on Train DLTK. Bad AI to abuse, no BA, and explosives everywhere make it easier than you'd think.

Miami A: Good, perhaps could use couch boost
Miami SA/00A: Murderfest, so hard to plan out routing with guards roaming all over.
Miami DLTK: Easy, just tedious. Colt takes 5x headshots to kill, and you can get double Colts. Lots of explosives to kill guards, just be patient and don't do anything risky. Very simple stuff for a seasoned vet.


Shipyard A: looks good
Shipyard SA: basically a scavenger hunt of collectibles, so just need a route really, probably worth finding an ideal pause spot, like for boosts or waiting on a door, etc
Shipyard 00A: SA + more scavenging
Shipyard DLTK: early Colt is nice, and while the level is pretty open and there are a fuckton of guards, there's so much architecture to work with particularly all the stairwells, the little fences guards can't see you over, etc. There's bounds to be a spot where you can super easily abuse them too. It would have a learning curve, but I think it'd be easy once figured out.

China A/SA: both look good route-wise, though the times can definitely go down
China 00A: SA route + cam pops, nothing too fancy, might be hard to live a good run though, so may have to take things safe
China DLTK: the start isn't too bad since there are lots of explosives and easy guard kills, but the ambush in the boardroom is kind of problematic. The three spawned guards all have BA, there's nowhere to hide, and I'm pretty sure they infinitely chase. Perhaps saving that section to the end and making a mad dash could work? Chaser guards tend to be blind until they arrive to their desired location, so it might work. The rest of the level isn't too bad, but it's long and tedious. Ammo also seems to be an issue. This level might honestly be pretty insane to complete, so while there are possible strat innovations, I'd say it's 8/10 difficulty for the moment.

Club A/SA: looks good
Club 00A: looks good, though Dusky could have held full speed more at the end
Club DLTK: very easy since guards are scattered, BA isn't an issue, there's lots of explosives, and lots of places to lure. You may have to slap guards though since the rifle thingy is loud, though that could also be used to lure away guards. Not much else to say really.

Grounds A/SA: looks good, but I think SA 43 is possible
Grounds 00A: obviously can do degen strats for courtyard golds, but I don't think R-leaning is necessary honestly. You'd want snipe kills on 1st and 2nd, then a sick mine throw for 3rd, 4th is easy. The rest is SA stuff.
Grounds DLTK: this probably looks intimidating at first, but having 4 excess mines, TONS of false walls to hide around, and no particularly difficult guards, this is honestly a breeze, you would just need to learn where all the guards are precisely, and where all the false walls are. For the start, toss a mine to boom the two guards and car on the left, run forward into the grass, then repeat for the pair and 2nd car. For the area around Goldfinger's car, you can lure out guards, then hide behind the door, plant a mine, and nuke a ton of them. For the car park, run along the left side grassy area, lure as many as you can, then run and hide in the little house to sneak by them all. Alternatively, hide behind the door in the little house and slowly lure them all over, then nuke them.

Airport A/SA/00A: looks good, but may not be maxed
Airport DLTK: pick off every guard slowly and try to keep them so you're only fighting one at a time. For the key guy, lure him somewhere with a wall and slowly chip away at his health, don't bother with AK and stick with pistol headshots, continue picking off guards with silencer until they're all dead. Lure out the chick and do the same strat as you did with key guy, except use Colt. It takes ~45 headshots which sounds insane but isn't THAT bad. Ammo isn't as tight as you may think, it's all about consistent combat.

Alps A/SA/00A: looks good, 2:17 probably not possible, 2:18s on SA/00A would be cooked
Alps DLTK: the level itself would be super easy, if only it weren't for the time limit. Compared to Agent, you only have 1:32 to kill every guard in the level, which is brutal. Some ideas include having the rocket guards blow up some of their friends, but there's really not a whole lot of time to work with. The only way I can see this feasibly being beaten is if you were to shoot guard and continuously stun them while attempting to run them over. Ultra degen for sure, probably 9.5/10 difficulty

Foundry A/SA: looks good, but can be pushed
Foundry 00A: Cyberia and JD use two different routes, but I'm pretty sure JD's is faster. Regardless of route, definitely run towards 3rd cam and fire at 2nd cam to save a bunch of distance. Holding speed can save a lot of time in certain spots. For the cam in the big boiler room place, it may be faster to hold full speed and do a whipping shot, ideally into the lens.
Foundry DLTK: pretty easy, just lots of patrolling guards. You can use the house near the start to lure and pick them off, and near the barrel tower as seen on Agent, you can do a big lure while blocking the door and blow up a pile of guards. Nothing much else to say.

Forest A/SA/00A: looks good, though perhaps some sort of yolo firing route could be better on SA/00A, or maybe grabbing a Colt could help
Forest DLTK: pretty easy, just lots of guards to pick off, but also lots of hiding places and false walls, particularly those spike plant things. If you destroy a drone gun without killing the gun, they'll pull out a Colt, which makes both killing and ammo management significantly easier.

Capture A: looks good
Capture SA: tape building->Tilly->Exit, for tape building definitely want to do a big lure and hope that you manage to pick off the one guy with the key and then heading down, can definitely get pretty yolo, health shouldn't be an issue
Capture 00A: okay revised 00A route: run to safe key, then GL, then tape, try to be quiet and use pistol throughout, then run to Tilly, and then car in the shed. After that head towards the far car and ideally hope the guard blows it up, or otherwise land a far GL shot on it as you run towards it, then go around the corner, bomb the last car near the end, and exit
Capture DLTK: GL makes this peanuts, just head to the GL picking off guards along the way, hide in the GL room and do a big guard lure using AK, wait for like 20s then boom them all while blocking the door, do a 2nd big guard lure on the lower floor = rip guards + happy ammo. Continue picking off guards with either pistol or GL as you see fit, then run to the end. With a far GL shot setup for the car in the corner, you'd even further reduce the number of guards you need to fight with. Possibly the easiest DLTK level to beat: 0.5/10

Prison A/SA/00A: tl;dr: go as fast as possible
Prison DLTK: bit of a slog to start as you definitely have to slap the first guard, shoot the 2nd one towards the nades to take off his BA, and then slap him to death too. Nades are very helpful, but the level has a lot of BA guards, so you have to really know who has what. There are also lots of ammos in the boxes, including 2x Magnums, which imo should be used for removing BA. Use nades as you see fit. Overall, pretty basic, but quite hard with all the BA dudes.

Ranch A/SA/00A: looks pretty good, of course can be faster with more insane strafing, but the level is basically strafe Goldfinger, have Pussy be loaded as much as possible, strafe her, run to CIA dudes, strafe Felix, leave. With Madoka's WRs, the only timeloss between them is just the split for Pussy. On Agent "Chic" to completion is 31->2:16, while on 00A it's 33->2:28, so figuring out how to keep her loaded and quick is all there is. Perhaps guards boosts can help, as well as better firing/less need for ammo. A/SA should be the same time, but 00A should only be a bit slower, like maybe 5s?
Ranch DLTK: no guards in the whole level have BA, they're all very spread out, and there's a ton of false walls to abuse. The only annoying thing is it's a lot of slapping. Pick off all the interior guards, then those nearby you can lure with the Karabiner from the balcony, then continue picking off the outside ones one at a time. After, get the Rumpus key and do the stable objectives. I suggest spending time to thoroughly learn where all the guards are and who can see you from where (ie: do practice runs), but you cannot die unless either you do a knowledge fail or do a patience fail.

Hideout A: looks good, but possibly improvable. Perhaps a guard lure to open the final shed is possible/faster?
Hideout SA: Galore->Gas Mask->Exit is fastest by a lot, so it's basically a longer Agent
Hideout 00A: before starting this, I highly recommend using Invisible/Turbo to roam around and get a feel for where everything is. It's really not THAT messy of a level once you know it. Start with talking to Galore and keeping your health as high as possible. After, go between the set of building to the other big shed where the first gas cannister is. You want to do all 3 with only 1 pause, so you need to keep your health high and rely on guard luck. After that, exit, go left to the 2nd white building where the 2nd cannister is, then leave through the side door. Head over to the far white walled area which surrounds the building with the 3rd cannister, and then continue to the next sub-area for the gas mask. At this point, you'll have an army of guards shooting at you, so start lighting them up. Run to the building where the radio is and fire shots to lure. You can either use AK for faster/dangerous lure, or Pistol for slower/safer lure. Hit the radio, kill as many guards as possible, then head out from where you came. Run to the nearest red brick shed across the other side and exit. This route is likely very difficult to live, so for intermediate runs, I suggest taking time to kill all the guards. A degen grind for a great run for sure.
Hideout DLTK: okay, this level seems like a nightmare on paper, but it's not unforgivably hard, you just have to be very fluent with where all the guards are, especially those outside who patrol. Start with going around the left side into Pussy's shed, slap the guards in there to death, then slowly pick off the guards inside and the patrolling one. Hug the left wall when leaving and wrap around to the tower to get the office key, then hug the wall again and go back and around. Head to the shed with the 1st cannister, slowly killing guards with slaps. Ammo can be tight as AK is noisy, guards have hats, and you have very little Pistol ammo, so always try to slap every guard you're able to. Head over to the storage area with the 2nd cannister and pick off the guards. Running across the street isn't as dangerous as you may presume, so long as all the patrolling guards are dead, and you minimize the distance and space you take up. For the white walled area, don't bother doing anything except the objectives (gas mask and cannister), as the nade, storage key, and ammo, aren't really worth it. Head to the radio building and slap all 3 guards to avoid making any noise or you'll surely die. When going to the exit, do not yolo your entry and simply kill the last guards safely as you had for the rest of the level. This level has a big learning curve and you need to be quite patient and knowledgeable of the guards with their vision in the fog, but at its core, it is a pretty basic level.

Knox: A/SA/00A: bad news @Dusky but you go the wrong way around the building at the end, it's like ~0.4-0.5s faster to go around the left-side. Otherwise though the runs look pretty good. On Agent, you can definitely do nade drops at your feet for easier boosts. On SA/00A, it's definitely possible to skip the Tank and hit the first two vehicles with nades. SA isn't that hard to live, but 00A might be too degen.
Knox DLTK: head left at the start to the building and lure over 3 guards and pick them off. Hug the fence and scale around the level on the left side and slowly killing guards until you get to the tanks. Each of them have their own ammo, so you'll probably want to drag both of them. Watch out for the 2x AK guards who have BA, you'll probably want to squish them. With two tanks, you can also do the "glass tank" strat as seen on Streets DLTK with some careful routing. Once you're at the fence area towards the end, the rest is pretty easy with all the false walls. Nades aren't too useful unless you have very good prime timing for quicker kills, but they're likely most useful towards the end of the level.

Vaults A: looks good, I'm not really seeing lower being possible without some new innovation
Vaults SA/00A: basically like Agent, but you have to do an extra bit of running around
Vaults DLTK: start with collecting the BA and both lower ammo boxes, then go to the bottom to where the platform where Oddjob stands. Strafe him into a corner so he's of sight from Kisch, kill Kisch, then grab the other ammo box. It takes a gajillion slaps, but if you have delicate positioning, he shouldn't be able to hit you, similar to completion strats on B2. For the lower area, you can do a similar strat but it's harder to setup. Once Oddjob is dead, just slowly pick off the guards towards the vault door switch, then head out. You can be as loud as you want as all the guards are deaf. For the protect, simply run to the first BA and camp there. There's only one guard at a time who can attack Macleod, and the rest chase you, but get lost in doing so. This means the protect will likely result in you camping for 2 minutes and maybe killing 2-3 guards aiming at Macleod. It's very easy. Oddjob is tedious and is the only hard part of the level, so I'd say it's not exactly the most difficult level in the game.
Vaults Protection Strat A/SA/00A: go to where Oddjob initially stands and simply check back and forth towards the vault door, and several feet behind Macleod (this is the only spot guards will fire at him from). Kill any guards who approach you, and fire at the attacking spot. Once the timer is low, leave with 8.10 or so on the clock. This works for all difficulties. Also since you're barely killing anyone, you won't be getting many respawns

Plane A: looks pretty good, but why grab the nade? Wouldn't it be faster to just shoot the box? @Dusky
Plane SA/00A: same as Agent but a bit harder to survive and kill. Ideally, they'd be the same time, but might be +1s, at least for awhile.
Plane DLTK: looks scary at first, but isn't too crazy hard. Grab the nade, all the ammo, and blow everyone up in the first area, then use Shotgun to kill the first white guard as he has BA. This should lure the 2nd white guard for you to also kill, and from here on it's a mix of box explosions to kill guards, hoping for frozen guard glitches, and slowly picking them off. You have over 4 minutes before Goldfinger escapes, so you aren't in a huge rush. At the end of the room before Goldfinger, make some noise to lure the pair of white guards in the back and kill them both carefully, then throw a nade in Goldfinger's room and collect the ammo around. Try to be quiet in the basement for better guard control, but if you're low on ammo, you can switch to Colt for 2x damage. Definitely use Colt for white guards. The timer isn't all that much of an issue, and it's more about ammo management, battling BA guards, and a little bit of guard luck with ideally, several of them frozen.

Crab Key A: looks good, but could be improved. You can charge full speed whenever you're in the pipes, but can't against the door when you're below it. Don't forget that you still keep full speed during a forced crouch, so you should be holding forward the entire time. Also for Dr. No, you can kill one of his guards instead to alert him, which would be slightly faster.
Crab Key SA/00A: Same as Agent for the most part, but surely much harder to complete due to enemy damage and health buffs
Crab Key DLTK: at first this might seem basically impossible, but there's a couple tricks that help. Start the level by slowly killing every guard. Guards drop 10 Magnum bullets while taking 5 headshots to die, so you can continually gain ammo so long as you're accurate. There are a fair number of explosives and false walls to help. Now, the starting part isn't too difficult by DLTK standards, but the ending is extremely tight on time. However, I discovered a trick: lure one of No's guards (ideally the left one), but don't shoot him, shoot at him, then slowly drag him all the way to the reactor room. Because guards can shoot almost freely in the pipes, regardless of height and doors being opened/closed, you'll have to do it with noise and extreme care. I haven't worked out the details of how to do this though. Bring the guard all the way to the reactor room, kill him, and then Dr. No will trigger the timer, giving you over a minute extra in time. Note that you can prevent spawns by looking in their direction, but this is not permanent and will spawn as soon as you turn away. Pick away at the guards as quick as you can from a safe spot. I suggest at the back corner of the master control. Also note that while Dr. No is inactive unless you go near one of the two entrances, he is vulnerable and you can still kill him. Give him a few headshots and then explode him. If you have any extra time leftover, use it up to kill extra guards, before resetting it to 1 minute for the end. You can use either the Colt or Magnum to kill the final spawn guards on the way out, and there should be plenty of time for you to do so safely. Overall, the level is quite tough, but not impossible. I think 5.5/10 is about right.

Island A: looks decent, but some very bad lines at the start where Madoka went the long way. For the obj A guy, run straight at him and blast him. The rest looks pretty good. Some general tips: killing the boss guy is all about speed since it triggers Rosa to run to the end, so don't worry about leaving quickly. Be sure to grab his key so you can open a gate for her, and then just keep her loaded. You can also bring the Forestry key guy more forward by firing Uzi shots as you approach him.
Island SA/00A: grab the nades at the start and continue as normal. Be sure to kill the Uzi guard along the lines as you'll want it later. For 00A, it's also ideal if he pulls a nade as you need 1 extra for the ammo dumps. For obj A guy, it may be faster to break speed and stop to kill him, rather than going around as the booby trap deactivates once he's dead. Once you enter the shoot range area, run to the right side and start firing an Uzi clip as you get to the brown rectangle on the ground. This will lure a guard out and then you can skip getting the Forestry key. Take tight lines towards the right-most ammo dump first. There's a very close BA in the small white building along the way, which can help survivability and also boost potential. Chuck nades at all 4 sets of boxes and hope they complete. For an intermediate strat, you could just shoot them, but eventually nades will be required. The rest is the same as Agent, but harder.
Island DLTK: nothing too fancy here, but a lot of basic guards. Start by luring the first guard to get a Colt. Even though you will gain +5 per kill with perfect headshot accuracy, ammo is still tight because of the end. Pick up the nades and for each area you find difficult, block a gate and spam shots to do a big lure. Make sure to hang onto at least 1 nade for later. If you'd like, you can also farm some guards for more. Slowly clear out the area until obj A guy, who will need to be killed carefully by making him animate and then blasting his face. For the big open area, lure guards over and pick them off, using the gate to block and bomb. Once cleared, throw a nade into the shooting range, as guards won't be lured out until you're close by. Try to kill as many as possible. For the fort section, repeat the same tactics, though you'll likely want to get at least 1 nade to do a big lure when you first arrive, but you can farm for more. If you're out of nades, open the gate into yourself and slowly reveal a crack until you can either hit guards or make them animate (ideally, throwing a nade). Clear out the forested area and before going to boss guy. For boss guy, the entrance door will always lock behind you, so you have to fight him. He takes around 65 Colt headshots, so you need to have a ton of ammo for him. He likes to roll around a lot like Baron Samedi in Goldeneye. One trick that helps is to rush back to the building you came from, close it, then double tap the door so that it's opened but trying to close. Boss guy is unable to open this door, so you can create a small crack to safely fire at him, while being able to back up if he gets dangerous. Overall, the level is quite long, littered with guards, and the final fight is pretty hard.