I use flapperons on my Katana, Extra, SSE and UCD. but only for braking before landing, or in combination with a 3D maneuver like maybe coming out of a hover into a harrier, or going vertical from takeoff. When using them as an air brake, you have to mix in a little elevator to keep the plane fairly level. A little bit of flap will create lift, too much will cause drag, and that's what slows me down for my short runway. I guess it would work for take off too. The only thing about flapperons is that they decrease your aileron effectiveness.