I think the Sledge will be the BEST .40 size airplane available when it comes to 3D and high alpha flight. I don't anything can beat it! The Top Cap, Su Do Khoi would probably be second place.

The Aeron will tumble around and flip quicker and faster, but won't 3D as well. It's still a great one though, from what I have heard. The designers of both airplanes cruise around on the forums so hopefully they will see this and throw in their input. Have a look at the FunFly forum if you want more-

There are also big differences in the kit.

The Sledge comes with EVERYTHING. It sure as hell better, it's $120! It comes with good pull-pull and all the hardware and wood to finish it.

The Aeron is just some laser cut parts and the plans. You have to supply the rest of the wood, the hardware, and all that good stuff.

The OMP Edge mentioned is closer to the Aeron than it is the Sledge when it comes to flying. OMP comes with all the wood, but no hardware.

If 3D is really your thing, get the Sledge! I just ordered one myself...