Matt, your concern about the viewfinders is valid, but in practice, it's nothing to worry about. Yes, these are older cameras, and they can get dirty. Worse, the prisms in the M2/3 can decement, leaving you with a tricky and very expensive repair, or a dead RF. But the good news is that full separation is a fairly rare problem, and it IS repairable (albeit expensively). A new camera can get dirty, too- have you heard about the gap in the eyepiece of some new MP's which let in all kinds of gunk? Whether it's an old or a new camera, if the finder is dirty, it can be cleaned; when this is properly done, it will remain clean, bright and functional for a long time. As for relative brightness, there are even posters in this thread who have noted the edge might go to a clean M3 over a later camera. Look around online, and try to find the technical drawings comparing the rangefinder mechanism of the M3 and the later cameras- I know I've seen this somewhere. Anyway, the M3 has a different design; it's very interseting. No wonder the M3 has never had any issue with flare. I think the M3 is the best M camera, because of the finder. 35mm shooters may prefer the M2- and finders aside, they are basically the same camera (except for the counters...). But as a 50mm shooter, the M3 is near perfect. Mine are both very clear and bright- as good or better than any other M I have owned. The high magnification and excellent framelines- with corners!- are great for the 50mm especially- but it's also a real joy with the 90mm, and even with the 135mm. The M3 was my first Leica, and when I later got an M6, I was shocked by the finder. It was a very late, very clean classic M6, but the finder was a bit dimmer than my M3, and it flared like crazy. No comparison at all, and I soon happily sold the M6. The M4-P that followed it was better- and it was nicer to use with a 35mm lens- but that camera got sold, too. I soon wised up and bought another M3, and now am happy as a clam. But don't take my word for it- try one. The bottom line about finders is that if you are going to buy one of the older bodies, look through the camera before you buy, or make sure you get right-of-return. Do what you can to get a good, clean one, and don't worry- odds are it will last a good long while.
Now some other issues- I don't mind carrying spare batteries. I always have spares for cameras that take them, and for my light meters. I have no problem with battery dependency. They are cheap, light, and easy to have around. There's no excuse for being caught without batteries. But it shouldn't stop you shooting if you are. I like my M3 for other reasons- and if it took batteries, I would carry them. But it doesn't- one less thing to worry about. As for loading and rewinding, which some folks complain about with the M2/3; I have gotten so used to M3 loading now that it's a non-issue for me. It's done pretty quickly, and once you learn it, it's fool-proof. Plus, carrying two or more bodies in fast-moving situations like weddings, I've never run out of film at a critical moment. There's always film in one body, and there's always a minute to change film when I need to. As for rewind, I like the knobs better than the angled cranks. I am not gentle with my cameras, and I broke the angled crank in my M4-P- twice. Besides, I always found my fingers slipped off the cranks part way through the rewind, and the film unwound. This is annoying. But with knob rewind in my M3's, the film always remains tensioned. So if your fingers always slip off the cranks like mine do, rewind is actually faster with the knob- plus, it's a far more robust mechanism.
As for the value of having two bodies, even identical ones, well, I wouldn't work any other way. I always want a spare, in case one jams or conks out for some reason (this has never happened to me in ten years of shooting with Leicas, but I know failures can happen); in case one is stolen, or one is in the shop. When shooting jobs like weddings, it's really nice to have multiple bodies, as I mentioned above. I tend to bring three or four camera bodies, mount a lens on each, and shoot with what's appropriate to the moment. I don't like zooms much- and they don't exist for my RF's anyway- and I don't much like changing lenses at weddings unless I have to, so multiple bodies are useful.
Anyway, it's very much a personal choice, and each of use works in his or her own way, but I would not be without my two M3's. I'd like to get a third Leica body, and after all the Leicas I have used and owned, I know I'll take and happily shoot with any Leica anyone will give me. But if I'm going to spend my own hard earned money for one, I'll look for an M2 or M3. They are very well made, beautiful, have all the features I need, and none I don't; they are cheaper than other Leicas these days, and with maintenance and good lenses they will work as well as any other Leica. What's not to love?
(Edit for typos.)
