Yep I have Group Fly, and they react as they normally do except in three dimensions 
They will fly closer tothe enemy to get attacks into range so I'd really only suggest using it to get into position for attacks (very handy for getting all henchmen in firing range where there is only a narrow ground-based approach).
Speed is a bit slower, and end-use higher than regular Fly. I've two-slotted for End Rdx, and can run it on it's own indefinitely or with Assult, Tactics and Dispersion Bubble for the duration of a single PvE fight.
cheers for the info mate
does any1 have this for a mastermind? if so how do the minions react? i.e. do they fly off to attack or always stay next to u?
also is it the same speed and end usage as normal fly?
cheers