When I use 6V Batteries (like in my Flip), I only use them with regulators ! Why risk if there is an easy way to prevent ? !
I bought my regulators from Central Hobbies so far, but will give MPI a try !

I use 6V Batteries depending on the plane. For my GeeWhizBeee for example, I think I will go 4.8V 1600 NIMH, but for the wilder 3D planes I try to use 6V !