This is going to sound crazy, but put a Super Tigre G90 ringed 2-stroke on a Twist. Trust me. I have a Twist with one and it's awesome. I'm running a lithium polymer receiver pack, so my net weight increase is only about 4 ounces over a Evo .46 setup with NiCad's, but I have 2.45 HP instead of 1.47. Amazing thrust, and the plane still flies light as a feather. You can never have too much power with 3D. Just barely squeaking by on power (1:5 thrust to weight) means you can't get yourself out of a jamb quickly. I like having the piece of mind that I can rocket out of a hover if I need to. And again, the weight increase in nominal, plane still balances, and the torque effects of the longer prop don't cause any problems. And the motor is only $120. You can't go wrong.

The Twist has some elevator coupling at knife edge, but inverted flight is hand's off. Knife edge loops aren't the greatest, but possible.