You may be able to pick up a used futaba 9C now that the 10C is out. That's plenty of radio for Pattern if you're on a budget. I don't have a 6EX but I think you may be able to fix your mix problem. I'll look into it for you.

If the plane is pulling toward the landing gear both ways (left AND right rudder knife-edge) you may want to try moving the C.G. further forward. That should minimize the pitch coupling a bit.

John Pavlick
Team Black Magic