I've been looking around toronto C-list, and some RB67's with lenses are only around 350.. I know its a heavy camera, but I'm used to shooting the heavier nikons with a 20-35 2.8, so I can't imagine it being terrible... or am I wrong?
I walk around with my RB67 and use it handheld in the street. A couple of things: the lens you use makes a difference. I have a 65mm and a 127mm lens, and the 127mm is easier to handhold (it is actually noticeably lighter and shorter than the 65). A good comfortable strap makes a difference. And after two or three hours you will start to feel it.