RE: why trex?
No, not really. If you had the money, I would suggest something bigger like a Nitro 50, or an electric 600, but if you are hell bent on a mini helicopter, then the TRex is the way to go.
Thinking about it a bit harder, a well equipped TRex SE (HS65 servos Futaba 401/9650 combo, Phoenix 35 ESC, Medusa 32-28-3400 motor, 2-3 batteries, a lipo charger and balancer and a good radio) will cost you about the same as a medium equipped 30 or 50 sized nitro helicopter (give or take $200). So the decision should not be that hard.
Rafael