I have been using my tiny little 35mm Olympus RC range finger for street recently. It is hardly ever noticed, I keep it to my side and palm it sometimes in one hand to shoot verticals from waist to just below waist height. The 40mm f2.8 lens is quite limiting as I find it not fast or wide enough for me. I have been shooting p3200 with it, not getting to many keepers though, the camera is tricky to zone focus too.
I get the majority of my good street shots on my olympus PC/om40, nikon em, and my f3, with a combination of fast 24mm and 50mm lenses. the first 2 bodies for their compact size, and the f3 as its just very comfortable in the hand and just works beautifully. i also like to zone focus and shoot from the camera hanging around my neck, it works quite well, but is not for every situation.
as for traditional focusing, the f3 is amazing fast with the P, G2 and H2 screens. The P is a general screen but with split at 45*, the G2 is a big fat center microprism, the H2 is the entire screen covered in microprism (very trippy). I have been working on the H2 screen as it takes a bit of adjustment, but I believe will be better off for even faster shots when you do not have to recompose after focusing from a center spot such as on the P, and G2 screens. Also used with a eyecup to block stray light.
I have also done street with a TLR, but thats a bit trickier and is not as fast. I usually focus on a spot and wait for people to walk into it.