Some interesting technical discussion going on here!
Good point about ABC fuselage being taken up by transmission. In principle, since each rotor only handles half the torque in hover over conventional, i am not sure why ABC would require a significantly larger transmission. The only reason i can think of is that each rotor would need to handle more torque during high speed manouvre, because advancing and roll upwards side doing more lift. The shaft and hub mechanisms would clearly need to be much stiffer/stronger, but this is true of any high effective hinge offset rotor.
Although inherently good lateral Cm comes naturally with tilt-rotor, i suspect that this would be offset by the need for more power/torque for the higher disc loading. I have no figures to compare on this point.
Dave, that's a handy resource you have there. Any chance of the two technical papers you mention?
1. Aerodynamic Design of the X2 TD Main Rotor Blade - Ashish Bagai (May 2008)
2. Dynamic Design Characteristics of the Sikorsky X2 TD Aircraft - R. Blackwell
(May 2008)
PS: Hardly even get time to check this site out now...
Mart