The first I took my quad out to test 2.5.3 loiter was a bit sketchy. The quad screamed from one edge of the field to the other, overshooting by a greater amount each time. (See below, it started somewhere in the middle. The pattern is about 35m across).
I dropped the Loiter P parameter to 0.2 and took it out today. It performed a bit better. The overshoots were more controlled, but it still covered and area of about 25m across.
Logs showed GPS was picking up about 10 satellites each time. Should I keep reducing P, or is something else at play here?