I used Reflex-IV for years, until it locked up on me. Had it repaired once, got another few years out of it. The advance lever cocks the shutter and raises the mirror, to puts a lot more stress on the rack than does the IIIS. I have a Reflex-III as well. The prisms tend to desilver; I replaced the prism in the Reflex-S with one from a Minolta XG-1, it is much brighter than the originals. It was a perfect fit, which was pure luck. I have ~20 Kodak Retinas going back to the 1930s. Bought out a box of Retina parts from a repair shop that was going out, learned some simple repairs. I bought a Deckel-F adapter to use the Retina-S lenses on the Df.
Schneider Xenon 50/1.9, wide-open.
Gunston Hall, Halloween by
fiftyonepointsix, on Flickr
Not too many rangefinder lenses can be used on a DSLR.
85/4 Tele-Arton on the IIIS,
Tele-Arton 85/4, on the IIIS by
fiftyonepointsix, on Flickr
Tele-Arton 85/4, on the IIIS by
fiftyonepointsix, on Flickr
The 90/4 Tele-Arton on the Df,
90/4 Tele-Arton by
fiftyonepointsix, on Flickr
These lenses used to go super-cheap. These three lenses ran me a total of $80. I put together the IIIS with 28/4, 35/2.8, 50/1.9, 85/4, and 135/4 for under $300.
The Nikon rangefinder from the S2 and up have 1x finders, as does the Canon P and Canon VI. It is nice to shoot "both eyes open". I use a 1.25x finder with the Leica digitals to get "close" to the M3 with it's 0.92x. The Kodak Signet 80 of 1957 also has a 1x finder, and has interchangeable lenses. Styling like a '57 Chevy.