I'm flying an Easystar with APM 2.11, it's had many flights and generally flies well. I have however noticed an issue in that the plane seems to overshoot waypoints when flying in a northerly direction, regardless of wind direction.
The behaviour tends to manifest itself as a tendency to fly northerly past waypoints before turning to the next waypoint. This issue doesn't seem to affect hitting waypoints in other directions, and has been noticed on a number of different days with different wind directions and wind speeds.
The plane's PID's have been tuned and I can't see how PID tuning could affect one direction only anyway. RTL tends to circle quite northerly as well. The plane will face north, fly quite a long way, then turn around then fly back but as soon as it is past the RTL waypoint, it turns again and flies an egg shape circle in a northerly direction.
Sorry if the above isn't clear, happy to provide more specific answers.