Gave it a go today. First time I've used the red knob. On the ground I killed it once or twice, not quick enough pushing back in as it faltered.
Airborne pretty much a non event as the speed keeps it turning. I noticed the lack of throttle response when lean but a quick push back to rich was no problem, ref the "mixture rich first when increasing throttle". Getting that back to front did no harm except to run rough till I richend it.
All in all not a problem.