Some of the statements there seem hokey to me. Like:
As air blows through the tail rotor in the direction it is blowing air, efficiency is lost and the rotor pitch needs to be increased (possibly leading to a tail rotor stall).
If this was true, airplanes everywhere would be stalling their propellers at high speed, as 'air blows in the direction it is blowing air.'
High level of yaw authority, extending well into the flight envelope. As yaw authority is not totally limited to that of the aerodynamic capabilities of a tail rotor, being dependant on that of the differential rotational inertia applied to each disc, being used to generate a yawing motion, operability extends beyond that of the tail rotor system.
What about autorotation? We have batted this back and forth before, I think in this thread. Coaxes and synchrocopters are bad here. Generally they need long tails & rudders to cope. Look at the KA50, the K-max, ect. Plus I thought it was differential torque, what is this differential rotational inertia thingy he refers to?
-- IFMU