I've seen t-rex's with power setups perform ballistic 3D moves faster than any nitro bird can. I don't own a t-rex, but from what i've seen, a micro electric is very well suited for 3D because of the huge power to weight ratios that you can achieve with them. A raptor is heavy and so the cylic response is slower in comparison. I'm not saying they're not suited for 3D, but for truly agressive 3D, I don't think you can beat a micro. Of course, they don't hold up well in much wind, so there is a tradeoff.
As far as sound, I think (big) electrics is way better than the ugly buzzing of a nitro motor
. With electric you actually get to hear your helicopter beat the air into submission. With nitro, all you hear is, well.. the engine. [
] That's just me though..