True. The batteries are getting better but slowly. The next gen or best cells I think right now is the 20700 and 21700. Sanyo (NCR20700B) and Samsung 40T and 50E for the larger version 21700. That's the cells I'd use if I was going to make a powerful and volume / weight efficient battery.

My own build pack right now.

4,58kg / 1000wh (218wh/kg) and  293wh / L

Super Soco TS pack 60v 26ah. 11kg power: 60v x 26 ah = 1560wh (nominal) (1560wh / 9,8L (17x17x34cm battery size))

7,05kg / 1000wh (141wh/ kg)  and "estimated" 158wh / L  calculated from battery size 

The TC pack will have a slightly higher/better value than the TS battery.