Pros and cons like nearly every design change, even a seeming disadvantage such as rotating mass can sometimes provide an advantage in certain situations - the gyro effects could provide forces the rider could utilise for either stability or indeed for the opposite - bicycle attitude...
It's bad enough trying to transport a 29'r - gonna be interesting to see how far one of these will overhang in a rear car carrier! Probably need a lwb van to avoid taking a wheel out.
Another thing you could try is a spline/12 point key tapped or pressed in with g-clamp - obviously this is a medium drastic option but might be worth considering if less damaging things don't work. Suspect someone's already taken the nice options away from you.
A couple of William Lawrence cabinets (only naming as there were made in my home town) and the classic, can't believe I'm the first to post a pic of one, G-Plan 'Astro' (can't remember what it's real name is).
I have some Manitou's similar to these on a bike and like you I initially thought they might not be up to the job - I'm glad to be wrong once again as they ride really well with minimum faff.
Sounds a great bike, looking forward to some pics!