Again i get the strong impression that Sikorsky have probably tried everything that might fly, in order to select the ones that work.
The use of compressed air driven virtual X-wings is pretty amazing (unless compressor goes phut).
Dave, transition is simple: The counterotating rotor, omitted for clarity in "Detail A", provides a moment torque for the advancing blades. The retreating blades, omitted for clarity in "Detail A", are feathered to minimise their impact on airflow.
Actually, i am not sure what to make of X-wing concepts. Perhaps when you introduce all the aerodynamic devices required to stop blade flex diverging, as Nr reduces, X-wing is the next logical step. The advantage over ABC is reducing the mass of one rotor and the lack of of reverse flow over feathered aerofoils. I have the odd feeling that the penalties would end up nullifying the advantages though. Reverse flow aerofoils will have vicious stall characteristics, due to the sharp edge. In theory the design could just rely on active blade twist.
Probably one of those ideas that floats around until another idea facilitates its introduction...
Mart