Copter-3.5.1 is now the default version available through the Mission Planner (and other GCSs). This has just a single change on top of 3.5.0 (ReleaseNotes)
- fix to RC input corruption when using Spektrum DSMx with Pixracer
So hopefully nobody except Spektrum tx/rx users on Pixracer will notice a difference.
Thanks to OlliW and Tridge in particular for sorting out this issue.