I had the GP GeeBee, and it flew great. It would perform knife edge loops with no problems. You could make a dive run down to the field, and lower throttle and still landed. Normal landings were very nice, land atcrawl. I had a TT46 pro installed in mine, and it was perfect for it.
Probably the only changes I would make during assembly is to beef up the landing gear mount a little with some additional ply. Remember to put the washers behind engine to get the proper thrust angles, it looks a little much, but it works. I flew the crap out of mine for a couple of seasons, and ended up selling it to a fellow flier for $20 bucks. That's about it, the plane builds up nicely. Oh, one other thing you might want to try, but it may not be recommended is to put your cap strips on only one half of the wing only before installing it through the fuse, install the non cap stripped side through the wing, and after getting it through the fuse, cap strip the other side, I had a time getting the wing through the fuse with the cap strips installed. Good luck, Daz...