I have a 58" Great Planes Cap 21 kit built in the mid 80s that'll 3D with no modifications. It was originally a 40 size, but we put a Saito 91 in it. Will do super tight waterfalls, harriers and harrier lands all day long and will do the most violent blender I've ever seen not destroy an airframe. It is very difficult to hover though, although admitadly I'm not the best at this yet.
I recently broke a Irvine .53 in on this plane, same setup, and it would still waterfall and blender, but not quite enough propblast do set the tail real deep for a slow harrier like with the Saito. That was on a 12.25*3.75, so that prop was about 2 inches shy of the one on the Saito. It was easier to hover though, probably cause it was more tail heavy. I actually got 1 clean rotation out of it, and like I said, I haven't mastered that maneuver yet.