Thanks for that.
It’s very possible that the different mix of FF and P/I is good advice so I’ll just keep this in mind for future reports and maybe add it to the wiki if it proves to help more people.
The quick oscillations after turns means the turn rate controller is becoming unstable given large shocks (which is what the L1 controller delivers when it passes onto the next waypoint). This shock is removed once we move to SCurves…