i would definatly recomend a mosfet if you are going to run an 11.1 lipo. it will help save your trigger from melting or ceacing to function from carbon buildup. just about any of the extreme-fire.com fets are realy good, the btcairsoft.com line of fets are good. and there are lots of people that make home made fets that are of good quality. ill try to update with thier info later.
fets that i would stay away from are: burst wizzard fets, acsu, any of the jg or stock fet triggers that are made by companys that make guns.