I just got my ArduPilot and put it into a Super Cub. I was running default parameters as a first test. I plotted the flight path in Google earth and did some analysis of the results. I have attached the log file as well. Based on this flight, I need to tweek the PID filters for this plane to avoid overcorrection. The offset from the road where I took off and landed might be from not waiting long enough for GPS lock. Also the takeoff and landing altitudes are above the ground.