It's small, but see the red and bold correction above...

I don't know if the 4s1p 10Ah pack would be more efficient, but runtime would be higher and it would be a simpler pack since there are only 4 cells instead of 8.

If the Gmaxx battery trays were wider, the 10k lipo's would fit nicely. At 155mm long its about the same length as an 8 cell pack and would be better exposed to cooling air. 2s is one cell high, so center of gravity is lower to.

Thanks for the correction there....