PaPa-NeGeorgeo - On reading both threads I would believe that the strength of the wing was the major concern in it not being recommended. It is a valid concern. If you beef up everything before flight it is going to be OK, with some exceptions.

It depends on the airplanes pitching moment verses speed curve shape. A flat bottomed wing with incidence setup is going to vary quite a bit.

I remember seeing a mid side Goldberg Falcon with a .40 on the front fly - it did but the wings could get some awesome dihedral in a quick pullup. I flew the same sized Skylark (low wing version of the Falcon) with a .40 but with sheet covering on everything that was fine.

I fly a engine size or two bigger on most of my fun airplanes but those are the ones I have built and know personally that they will be strong enough, they also all have symmetrical wings. They just go faster.