Godfrey, don't forget you are comparing fixed lens cropped sensor to a IL full frame! The X2 performs excellently with sharpness and through the ISO range, processing and handling is an improvement over the X1, but that's about it.
The M9 will always give you the more accurate focal length angle of view over the X2, it will also give you the correct DOF, being more narrow wide open, and then you have the choice of any 35mm lens allowing you to go wider in apertures. As far as I can tell with the new M it will very likely give you better higher ISO performance, being newer and CMOS.
Traits shared of being full frame shared with the RX1 at f/2. Speculative, but arguable.