Here's some comments from Garett:

I would personally choose the Extra over the Edge. The reason being, the Extra will fly the IMAC style of flying much better than the Edge on a one to one basis. People say the Edge is better than the Extra in the freestyle. In my "opinion" and Edge is a great learning tool for 3d, But once you have figured out what it takes to do all the 3d stuff you can actually get allot more out of an Extra for the 3D. The edge does things like harriors and popup's pretty darn good. But it lacks in rudder power. The tapered wing on the Extra allows the plane to break away in the hard 3d stuff. The wing on the Extra is a little farther back and has the tapered leading edge, so this provides a arrow effect. The Edge has to push the straight leading edge around. The Fulkrum point of the wing on the edge is much further forward. This gives a drift feeling while flying the plane.
So in my opinion the Extra is a better all around plane. If you notice, there are not to many Edges in the past TOC's, and there are none in the top finishers!! Take this info as a grain of salt, but I have flown pretty much every brand, and style of plane on the market.
Garrett Morrison