You can have your control movement too small to control the aircraft. I took a guys Bipe up and I had one difficult time adjusting the elevator. One benefit you have if you are using a computer radio is to change your control limits while the plane is in the air. If your instructor or test pilot is taking your plane up, you should be right there ready to make adjustments to the radio. You should have been able to adjust the throw on your low rate setting to improve aircraft performance.