When i got my Hassey 500 C/M, i decided to try some street photography with it as well. My experience with the camera so far is that people hardly take notice of me. Perhaps it's becoz i'm always looking down at my camera (thru the waist-level finder) and they're not quite sure what i'm doing. And certainly, the Hassey is not quiet - but it doesn't seem to be a problem or get in the way of street photography.
Well, it's a huge chunk to carry around though as compared to a Leica or a Bessa.