Help with lipo's and west london racing centre

[MILKY]

Have been out of the loop for a while and come back to the sport and lipo's have landed!!
What difference can i expect compared to the 3800 nimhs i used to run in terms of power and longevity,presumably i wont need so many sets of batterys?If not how soon after a race can i/should i charge them..dont want my new beasty literally on fire while racing!!
Any help greatly appreciated.

ps running 1/10 touring,most likely 13.5t stock