At the risk of blatant self-promotion, take a look at Rangefinder, Equipment, History, Techniques, by Roger Hicks and Frances Schultz, ISBN 1-86108-330-0, GMC Publications 2003.

I've been using RF cameras since about 1970. They ARE different from SLRs and what you get for more money is (usually) an easier camera to use, though not necessarily better quality.

Cheers,

Roger (www.rogerandfrances.com, where you can also see more about our books)