Personally, if I was a shooting weddings for money, then I'd want a camera I could afford two of. Also, you have to be OK with a limited number of focal lengths. I saw a wedding shoot whilst I was out and about at the weekend, the guy had two big DSLRs with two big lenses. He was shooting from a distance of maybe 50 yards, so I guess he was after a certain "look". Is that really viable with a range finder? Also, I see lot of shots, close ups of the bride and groom holding hands, so you just see the hands and the ring, is a range finder ideal for that sort of thing?
Maybe you don't like those sorts of photos, and maybe you'll tell clients you can't/won't do them, but that's up to you.
As a hobbyist, I can afford to say "Woo! Pretty cameras!", as a professional, taking money for services, I'd have to think about what is best for the job. For a certain style, a range finder may well be best for the job, but from what I see around the web these days, I think an SLR (film or digital) should certainly be considered, at least as camera no. 2.