Oh man, I ask myself this all the time. Why RF? I consider selling my Leica every week. I only own an M4-2 and a couple of (relatively) cheap lenses, and for me that seems a lot of money tied up in a camera when I could get a film SLR and lenses for much cheaper and spend the change on film.
Then I pick up an SLR with a 28 on it! I don't like the diameter of the lenses and how much they stick out, the blackout, the way you see your focus. They're the main things but its enough to make me keep my rf for another week, every week.
I think I'm a bit strange though; I also love using external finders for wide lenses (wider than 35mm). As oscroft said, the temptation is to focus with an SLR even if the dof covers it, I find the same problems with moving framelines sometimes! The simpler, the faster, the better. For me that is.
However, for me, that these cameras are film is not a problem. As with SLRs, every now and then I think I have to start with digital. Then I realise that it may save me money, time, etc, but the trade off would be that every time I got the shot I'd be devastated it wasn't on film.