I'm in the market for a film M, but I guess due to previous experience, I wouldn't buy another M6. I didn't feel that they were made with the same degree of quality as, say, an M2 (which I owned concurrent to the M6). I actually called Gerry Smith at Kindermann (Canadian Leica importer) and had a good long chat with him about how crappy I thought the M6 was (or at least my particular M6). Screws coming loose, and just a general feeling that the camera was just not ready for prime time. Had to send the camera to him twice to resolve some really unnecessary things. And I felt bad about it at the time, because not only did I buy it from Keith Matson at Gallery Cameras in Toronto (THE best Leica store in Toronto at the time, or even in Canada for that matter), but I really like Gerry and I hated dumping on him like that about this camera.
Of course I say that, and right now I have an M4-P on my mind. Quite likely going from the frying pan into the fire!