For Moon Fest event, buy the 2000 dumpling CE copy?

I was looking at a discussion about the last run of this event (not sure if it was the original or the JP rerun), and there was debate about whether the 2000 dumpling copy of the Moon Fest CE was worth it.

If I read it right, it has a +3 dumpling drop (+4 if MLB, but the odds of that being the case initially are probably low unless you have copies from the last time), and looking at the Goddess difficulty quest, it drops 10-11 stacks, so you'd get somewhere between 30-33 extra by having another copy. At 2000 cost, this means you'd need to run the quest about 60-66 times to break even. With just using natural regen, you can only run the quest 7/day or 49 in the week (but you'd first have to unlock the goddess level), if you use almost every single AP you get. So, it appears that it is not worth it, unless you use apples.

Anyone see a flaw in my thinking?

Oh, one other question... some parts of the event guide here has the free quest AP going 5/10/20/30/40 and others have it as 10/20/30/40/40. Anyone know which is correct?

EDIT: Just noticed one flaw... I didn't realize that Moon Fest also increases the rare dumpling drops. But the goddess difficulty doesn't drop rares. If you were to farm expert instead, you'd get on average +20 normal and +10 rares. Thus it would take longer to break even on the normals, but you'd be getting more rares. I'll have to study the shop more...