It was about 10 years ago that my Dad said to me (and a few others) that Lipo's from mobile phones (as that was the only place they were commonly used) would definitely be the future, and he said you can imagine the battery being a clip on section to the bottom of the chassis, exactly the way a mobile battery clips on to a phone...
Would make perfect sense to me, get the weight as low as physically possible and have it designed perfectly to fit
