From what I understand 50/80 choco in phase one just make Solar Blast do 3 or 5 times more dmg, but no bonus dmg to what girls do, which would explain why my girls did same amount of dmg to 6 lvl 1M hp boss and 1.5M 7 lvl one (I used 20 chocos on 6 lvl, and used 50 once on 7 lvl).

Only question is, how stronger boss will get with each level and thus how less dmg per used chocos and less event currency we will get. Seeing how phase two shop is barely 25% more expensive than first, when before it was like 5 times more, can suggest two things - or the event will be really easy, or the difficulty of bosses will sky rocket slowing down stamina->choco->boss dmg->event currency really, really down.

Thou they could make the event easier as an compensation for it starting over a day later.