I personally do not like the idea, why turn the power off if you don't have to?
Understandably leaving the engine at idle causes more drag as the air flowing over the prop acts as a sort of airbrake et al.
I practice simulated engine outs and it was drilled into my head that you don't turn the mags off.
Understandably I trained on a trike that was started with a prop-swing and a restart mid air was not possible.
Another thing - remember to turn the mags on again immediately after the engine dies so you don't sit there swearing with your hand on the starter button
