That is an interesting design, but the first ideas I had of how to implement lead to the device turning (either Yaw or Roll) when the stopping (Pitch) torque is

That is an interesting design, but the first ideas I had of how to implement lead to the device turning (either Yaw or Roll) when the stopping (Pitch) torque is applied. This seems less than optimal! What I like about that however is that turning (and/or coordinated turning) could be implemented without requiring leaning over... that means you could have extremely tight turning radius! I always thought of these Monowheels as simply a rail car inside a large wheel... which has pretty limited advantages, while the momentum of the outer wheel has definite disadvantages. Now perhaps a flywheel in the opposite direction of the wheel (but planar with it) could be used to apply stopping force (without the yaw/roll) up to the limit of friction? The view issues could now also be resolved by simply putting cameras (or even old-timey periscopes) in so you could see straight ahead.