for my receiver after experimenting with couple of NiCD and NiMH i have installed a 2cell LiPO 2100 mah and a regulator to bring the voltage down to 4.8v. It takes approx. 1.5 hours to charge (imax balance charges. Works with wall outlet and car battery) and gives me 4~5 days of flight (3~6 flights a day). Infact never brought the charge to 25% so do not really know how much more time it will give me. Also the weight of the whole setup is less than other battery packs .
I wish i could get the same setup for my 9Cap transmitter also.