Well,

A NiMH pack of adequate size will work just fine with your trickle charger, but digitals eat lots of power. I did not catch what plane you are going to be putting them in, but you could go with a 6V pack or even Li-Ion batteries, (not lipos).

I wish I had started out using 6V and regulators, (in larger planes only). I am now switching everything over slowly. With those digitals, get an 1100 MAH pack or larger.

What plane are you building anyway...some of this may be overkill.

Good Luck!!