RE: 8.8lb plane with a .61, how will it fly?
I fly a seagull Decathlon with a GMS .61 in it. Once the engine was broken in and decided it wanted to run it flew great. I have a set of GP floats that I put on it from time to time and I know that it bumps the weight up to around 10lbs or so. It flys well and will do rolls loops and stall turns fine. I think that at 8 lbs you will be fine but don't expect 3D perfomance.