I have had screw-mount Leicae now for almost seven years ( hardly a fort-night ), and they have become my go-to film camera.
My user kit is a 1934 chrome III, with: 3,5 cm Elmar, 35 mm Canon f:1.8, 50 mm Summicron, 90mm Elmar, and 135 mm Hektor. All except the Elmar 35 are coated. Also in the kit are: Nikon Varifocal finder, barn-doors for the 50 mm, FIKUS for everything else, manicure scissors for leader prep, and a light meter.
Last year, a good and trusting friend loaned me his mid-1950's M-3 DS kit so that I could experience that aspect of Leicadom.
I have shot several rolls with it, with good results, but so far have not liked it enough to seriously consider buying one of my own.
Pros:
> open back for easier film loading
> Single, large, bright VF/RF with internal frame-lines.
> Lever-wind
> Integrated meter connection with shutter speeds
Cons:
> large size
> heavy
> expensive
> lenses are larger and heavier
That said, I'm VERY used to my Barnacks by now.
The M is an all-new camera, and takes some getting used-to.... folks complain about the LTM being "fiddly"... the first couple times out with the M-3, I found that damned Leica-meter to be pretty darned "fiddly" and cumbersome.
I will say that the combined VF/RF is beautiful, and probably the single biggest advantage, as far as I'm concerned.
For the price of the M and M-lenses that are not duplicates of LTM, I think I'm happier with my Nikon S-2 kit: I bought a nearly-mint body with 50/1,4 and 135 lenses, hoods, and cases, Varifocal finder, and some sundries all for less than I could buy just an M-3 body in similar condition.
But then, the Nikon S was the very first "real camera" I ever saw / used.
For what all that is worth... I also like and use Exaktas, in spite of having Canon FTbQL, Pentax Spotmatic, Minolta XG-1, and Olympus OM-10 kits...😱