I think that both answers are correct. I.e. the ability to widely vary the RRPM without damaging oscillation, plus the ability to operate at very slow RRPMs without excessive coning.
The related patent is US 6,007,298. As I recall, Karem also received a later patent that is almost identical to this one, except that it is for a tiltrotor.
slowrotor,
The idea could well be a good one, however it may not be meet your objectives. I believe the intent is for this rotor to operate near the optimum lift/drag ratio. This maybe ideal for an unmanned UAV but the increased possibility of stalling the rotor is probably not too attractive for a maned craft.
Dave