You generally want more batt than you need so your setup runs cool. Batt will def get hot and not last if you get one thats undersized. Best thing if you can compare notes with someone running same setup and see what they've been using for lipos. Amp draw is too variable so you won't find general guidelines. Sometimes you can find data from someone using a data recorder posted on forums, but best bet is to find another running the same setup.

Personally, I'd get the higher rating.