Another vote for technique over equipment - don't sit there composing your shot like you would with a view camera on a tripod - if that's how you work, you'll end up drawing everyone's attention even if you're shooting with a pinhole with no mechanical parts whatever. I make a terrible street shooter because most of the time I do work with a view camera and I'm thinking about "Is that finger-tip still in the frame? What about that wire? Does that shrub look like it's growing out of someone's head?" and I take too long composing the background and then the subject notices I'm pointing a camera their way. When I practice quick and loose shooting, not worrying about the composition so much, my Contax G2 with its noisy auto-focus is absolutely invisible.