Yes, I just shot a bunch of film with the CV 25 (first edition, scale focus) mounted on a ZM and was gernally pleased, but certainly not blown away. Most shots were in focus, but I must admit my framing wasn't as accurate as I had hoped. It's a decent lens, but I think my beat-up SLR Nikon 24mm 2.8 is better. (And I almost always prefer rangefinder glass except in this case. My Contax G 28mm is fantastic.) I think if you shoot a lot with the 25mm, go for the Zeiss. If 25mm is only an occasional focal length for you, go for the CV.
Joe