The smaller the better. The Pico and Pico+ servos are good for the Moth or any servos around 6 grams, 9 gram servos are on the heavy side but usable especially if going dual IPS.
I just got my 4 cell Kan 650's from
Robotic Power Solutions so in will go my dual IPS.
Check out the Moth in this link.
http://www.rcgroups.com/forums/showt...light=menehune