At that size it's a tough call. I don't have any experiance with the small 4c's, but if they are anything like the bigger saitos they could make good little 3D flying engines, but sound's like your gonna need something a bit different. Maybe the piped 2c is what your looking for, something that could get you up through the moves and back in a hurry.

8178 made a good point, at this size a piped 2c will take a little time to "spool up" but once it does youl be of the ground and into your 1st manuver way faster than any 4c setup at this size that I know of. The only thing is the timing of the throttle will be laggy. If you were looking to compete I think the piped 2c would be your best bet, but it does not sound like you intend on competing so maybe experimenting with a 4c setup would make for more controlled aerobatics.

Basically I don't know, but I like to talk about it