His damage has been going up. He's finally replaced his Lightning Conduit trait (thank god) and he's obtained an Inkpod. I was taken aback by his improvement on Sivara after the patch, because his DPS went up 9k, and I'm not sure if Legendary Cloak, a new trait, and Inkpod really amounts to that much. A small critique I have is that on our recent Ashvane kill is that he could have done a better job of lining up Coral with Ascendance/CLF in addition to the Inkpod proc at 30%.

I think it's important to look at his DPS history per boss in EP. Of course he's developed familiarity with each boss over time, but there are some fights where he played Enhancement for weeks, then he plays Elemental once, and his Elemental DPS is higher. In 8.2, his Elemental logs are better than his Enhancement logs on Behemoth, Orgozoa, and Queen's Court. I've swapped to Enh on Ashvane and no one really bats an eye, but the melee vs ranged differences are more noticeable on say Queen's Court.

Should he be asked to swap any time we need more ranged? Would he swap on his own? Should/does he look at a boss every week and think how he can do better as Enh (or Ele) compared to previous weeks? Does he care to or should he be expected to? These questions are still gray to me.
Something I appreciate about Vonn is his willingness to use Wind Rush Totem (I can go on a huge tangent on why this is important to me). You'll see me running this on majority of bosses in Ny'alotha; I think it will be particularly critical next tier, and I believe that even with the addition of Stamp Roar, the more speed boosts, the merrier. I think the next step for him is learning to identify when to use WRT and not drop it down for memes.

Final Thoughts -
DPS: Improving, and I think the next step is to look at the minutia per boss to improve even further.
Mechanically: Seem fine, as no major flaws have stood out to me.
Socially: His sense of humor doesn't really match mine, but this isn't very important. I think he vibes with the guild well.