25 mm (1 inch) up/down and 25 mm (1inch) aileron travel is in my opinion a good value to start with.
We fly our roo's off grass strips. To get it airborne we have 55 mm (2,25 inch) up elevon travel. Since the turbine is on top of the aircraft, it pushes the nose down. A dual-rate switch, witch is programmed at the gear switch sets the elevon travel to normal values for flight. When you fly off tarmac, 25 to 30 mm (1 to 1.25 inch) is enough to get it airborne.