I think you guys are arguing somewhat different points.

using the same make prop
If a 24x8 is doesn't load up the engine it would probably be the best all around prop especially for IMAC (Plane should fly slower, have a stronger upline and better downline breaking)

Dick is right about the smaller 22x10 prop being better for 3D on large aircrafts. If all you were going to do was 3D period I would probably use a 22x8. Other than not loading up the engine, the reasons are that on our lightweight planes, a large prop will hover our planes at around 1/4 throttle. With the engine needing only a few RMP over idle to hover, harrier, etc. you do not have much control over the tail. With a smaller prop turning more rpm, there is a tighter wind tunnel staying closer to the fuse resulting in much greater control over the tail.

The .46 is a horrible comparison to a large gasser. The reason we use the flat prop and large diameter is b/c we need to tap all of the available thrust (we don;t have 60-70% of our throttle on reserve)

hope this helps