Haha, that makes sense now Trev!
Big nipper guy's do use a cheaper one way bearing. It sometimes locks up but the majority of the time works fine as they turn the power off just before they hit something. That saves alot of the issues your thinking about. They use it directly on the end of the motor shaft. I'm still considering a few options for myself - working out how on earth I can put 11kw of brushless power into an axe and make it work reliably! I look forward to seeing it!