The Leica's are just too old and cheaply made except for the M7. M6's and M4p's all break down in the rewind section and are thus overpriced.
I have only experienced the Leica M4-P, M3 and M2. I still have the M4-P and the M2.
I got the M2 before I realized what I had and then beat the hell out of it. It seemed not to care. It has not been serviced since 1982, and it works just fine. No wind problems.... ever.
You can get a get a pretty good M2 for $800.00 +or - and should realistically last a life.
The M4-P has been with me since 1987. It has had a motor winder attached occasionally. It has stood up very well over the years with NO service whatsoever since I purchased it and no problems. None.
The cameras are extremely well made, as they should be because they are also extremely simple mechanisms.
The "overpriced" part? Well, I believe this to be somewhat true, particularly the lenses which are certainly prohibitive, cost wise.
But: I cannot find a camera today as basic, simple and reliable save perhaps my Nikon F2.
The rewind section will outlast this operator, and many more.