I have a pair of black MX's, that I bought from the original owner who was a professional photographer. She purchased two complete MX systems when she graduated from school. I bought the whole lot off her, which included the power winder, the M 50/1.7, M 28/2.8 and a 135. The kit also included a pair of Metz 45's. The all-manual MX makes a nice match to an automatic flash like the Metz, and seems a perfectly sensible way to shoot professionally. With the winder attached, the MX is still amazingly small but much improved ergonomically.
These MX's are in nice condition. "Professional use" seems to have shown up in one of the bodies' rewind shafts being slightly worn, but otherwise both cameras are without issue and look like they are 5 years old, not 30 years old.
It's good to know about the good meter in the MX. I have hesitated to rely on an old in-camera meter, but when I do the exposures are accurate.