aka...they couldnt work the bugs out of its operation. Interesting as the sail fairing was one of the key peices of technology that differentiated the X2 from the XH59A. Had the XH59B been built and taken flight, it would have been largely the same aircraft as the current X2 minus all of the FBW controls.
Remember that something like 40% of drag was from the rotor mast, so flying without the highly developed sail fairing on it is a pretty big deal IMO.
One major concern for the X2 has got to be fuel burn in addition to noise signature. SAC has been mum on these points.