PBF
As for the shut down check, I just set 1000 RPM and cycle the mags Both/Left/Right/Both. You will be able to see the mags cutting out and the chance that the mags will cut out normally, but be live with the mag switch I the off position is extremely remote
Sorry can you clarify, are you saying doing a quick OFF then back to BOTH quickly is not really of value due to the remote chance of this OFF function is not working properly as opposed to the risk of not doing it quick enough and causing a backfire with potential hardware damage