UBEC or reciver pack?

Well, we found out my thermalling was the BEC getting too hot. So, we pulled the jumper and it ran fine on a AA receiver pack. Obviously, that is just for testing.

So the question is, UBEC or receiver pack. I'm leaning towards UBEC because of the simplicity and small size. My son wants to go receiver pack because it costs less and does not draw from the motor batteries.

So what do you all think? If we go receiver pack, how many runs can I expect to get out of it? If UBEC, how much does it draw from the motor packs?

Thanks,

Chris