This thread is actually turning into an interesting discussion on where the boundaries lie for what folks consider to be a helicopter. Part of me can't help but hear the nostalgic cry for the way things were...
heli1, what i understand you to be saying is that Sikorsky/Schweizer engineers should have compromised the design, maybe by tilting the rotor system to do away with the pusher prop, in order to keep the coveted title of "helicopter"?
Let me turn the problem around by asking what anyone has to gain by denying X2 the title "worlds fastest helicopter"?
Also, regarding tail-rotor/pusher-prop then i wonder how long it will be before the prop becomes teetering to remove any sideslip/climb pitch/yaw cross coupling. Once this happens then how long before a cyclic mechanism is introduced to improve yaw response characteristics (say FBW to vector powered flight and autorotation correctly).
Personally, my interest in X2 is that it promises to bring high speed helicopter flight to the wider fleet which is constrained on landing/hanger space and operational cost. What it is called does not affect my interest in the ship.