I really hope you don't go silent; I'm grateful for your input. However, some of the things you've said in earlier posts seemed to say, at least when I read them, that nothing but the close tolerance stiff system would work, and I fear that others will read them the same way. I'm glad to know that I've been wrong about how you feel about other designs and I'm truly sorry if I offended; that wasn't my intent.
I certainly wasn't advocating the use of car transmissions in a/c. I only mentioned it as an extreme example of what one might get away with, if resonance is avoided (and the system isn't simply overpowered). That particular builder was just fortunate enough to avoid danger points in flight, by luck; not design.
Just out of curiosity, how many of the Powersport drives are flying on rotaries now? Any idea on number of hours on the highest time unit?