Sure it works with either (any) origin.
Yes. It is more conventional to take cg as the referance.
I think (unimportant) that in this case it is more instructive to take the hub center as the referance - as it's not really an inertial problem - maybe you can see the benefit of it?*
Incidentally do you know the other useful unit for describing gravitational strength: gravity; 9.81 Newtons/kilogram
* you wrote:
"Fundamentally, Q, the height of the MR and TR from the CG are important even in steady state hover because the forces are actually** created about the CG, but your view of taking moments about the hub is correct providing you follow the same convention all the way through your analysis."
- My 'zero at the hub is 'nicer' for this bit - since 'cause' and 'cure' become two independant functions. Whereas in 'yours' if you knew how high the TR was from the CG you still wouldn't know if it were going to tilt left or right yet.
**I'm not sure I like the referance to "actually created about the CG" - since they are 'actually created' about anywhere you define.
- Slavery to convention
