The Kokams have to be heavy to withstand 42 Amps continuous draw. There's still no getting around the laws of physics, specifically thermodynamics in this case. Mass to absorb heat, surface area to dissipate it.

A while back I went 12 rounds with a chap who started in about "LiPo math." NOWHERE has anybody said that 2100mAh will give you longer flights than 3300mAh given the same current draw (throttle levels). NOWHERE! That's just plain foolish.

There are two ways that LiPolys can improve your flying experience:

1. Decreased weight. Saving a pound on a 6lb airplane is a MAJOR improvement. You need less power to overcome lift induced drag.
2. Increased capacity for the same weight as NiCd/NiMH. You can pack a lot more mAh into the same amount of weight and space.

Normally, we work with a combination of the two. We get some weight savings, and some additional capacity. On smaller park fliers, it's easy to increase pack capacity by factors of 5 or more. When you get 5 minutes on 150mAh NiCds, you're going to get 30+ from a 1020mAh LiPoly.

BTW, you only need 4S1P to equal 14 cells. That saves you even MORE weight, and you can still double up on the Kokams and save about half a pound over the GP3300 NiMHs.