Loaded Dice

2: 35%
3: 35%
4: 15%
5: 15%

Average hits: 3.1
Silk Scarf is a 20% boost, to match you need 3.72 average hits
Life Orb is a 30% boost, to match you need 4.03 average hits

2: 15%
3: 15%
4: 35%
5: 35%

Gives 3.9 average hits

for base 25 hits, that's 97.5 power on average. Not too bad.

BUT is it worth the item slot?

Most of the Pokemon that would actually use multi hit moves competitively use the ability Skill Link which guarantees 5 hits, which is a massive damage boost and doesn't use up your item slot.
The Pokemon that may consider this item are ones that do not have Skill Link (Breloom), or that have an alternative ability that may be better than Skill Link.
The main examples are Technician Pokemon in Ambipom and Cinccino. But even here, Skill Link + Life Orb will outperform Loaded Dice + Technician, unless Loaded Dice can guarantee either 4 or 5 hits