Zeropointbug - I have just received my Neu 1512 2.5D and am pondering exactly the same thing as you - A123 7S 1P or 2P?

I'm keen to keep voltage high so I can keep current low - after reading about the heat issues with Quarks and other ESCs.

I hope to be up and running on at least 7S1P by next week so will post my findings here. I was thinking of making 2x4S1Ps and 2x3S1Ps for flexibility - that way I can put a 4 on one side and a 3 on the other, or a 4&3 on each side of the truck. Excessive?