I would vote for the S2. If long life is your concern, the S2 is 55 years and going strong. It was built to be the highest quality professional camera in an era when durability was a benchmark. The repairs, if any, are basic. This camera is likely going to outlive the general availability of consumer film cassettes. The basic mechanisms within the camera are understandable to any repairman who does Leicas or other mechanical cameras.
The C/V R2S in a decade will be a 10-year-old camera that was never built to professional standards. Longterm,it will be harder to get repaired and will probably need more repairs. However, I have never owned one so am going by paying a lot of attention to others who post here.
Advantages of R2S:
- light meter (old RFs require you to use a handheld meter and to learn more about light)
- faster shutter shutter (there are times when 1/2000 is handy)
- faster flash sync - 1/125 vs 1/45 (outdoor fill flash is a little easier, though also a disappearing art for non-built-in flashes)
- More flexible viewfinder ... frames for 35mm and 85mm lenses
- What most people describe as the easiest to see RF focusing patch of any Nikon-related RF camera.
Advantages of S2:
- It's a classic, a fully functional piece of photojournalism heritage
- Owning an S2 with 50/1.4 gives you a direct link to the camera/lens that firmly established Nikon -the lens is a legendary part of 1950s photography that remains fully relevant today, and the camera is a direct ancestor of every modern professional Nikon.
- No meter wiring to break (however, its half-century-old flash-sync wiring might not work)
- One of the most durable shutters ever built
- life-size viewfinder -- this is a hallmark of Nikon RF cameras with the S2 and later. For some people it doesn't matter, but once you get used to it, it's a fantastic feature.
- Long RF baselength. The lifesize finder and the longer distance beteen the RF windows makes for extremely accurate focusing of fast lenses. This camera is a dream with a 50/1.4 and 85/2 and 105/2.5 -- my RF focusing is significantly faster and more accurate than with an SLR. The R2S has an easier to see finder but much much shorter baselength.
As for the 50/3.5 versus 5cm/1.4 -- with the Nikkor, you get 2 1/2 more stops of light, enabling the low-light shooting that is the hallmark of these camera. It's also a historic lens, what the majority of people considered to be the best of the 1950s (it's quality forced Leitz to improve their fast 50s). However, it has some quirks that show its age. it will flare in some backlit situations, and the design can show halo rings in harsh contrast such as bright streetlights at night. Wide open, it can have an antique effect as though you've put thin gauze over it ("veiling flare"), though this effect disappears with just a tiny bit of stopping down. Some of the out-of-focus areas in the background will be "harsh" with doubled lines that can be distracting (or show dynamic tension, depending on your taste). Obviously, the CV 50/3.5 will have modern optics, supreme sharpness, making it ideal for well-lit scenes and magazine-type photography. Its coatings will allow for the best color rendition. It should have the "snap" of a modern fixed-focal-length lens. Well-controlled out of focus areas.
S2 versus R2S is a bit like the difference between a classic and a classy curiosity.
I got an S2 because one was available and I liked that it was an ancestor to my SLR Nikons. Beware, though, I quickly got hooked on the Nikon RF system and found that it actually fit my shooting style better than the SLRs, but at a much higher financial cost.
