From soneone who has flown the GP Ultimate for three years now and loves it...... use the OS 70 (what I use) or the Saito 82..... personally, I am an OS flyer but you won't go wrong with either.... I would not go as far as the OS61FX due to the weight and size..... don't over power this plane without building in some strength. This is a fantastic flyer when built stock; the OS 70 moves it around very nicely.....

Build straight and enjoy.