James,
Contax Aria is one lean, mean, picture-taking machine
Aria is my one and only body right now and I'm looking for a backup Aria or S2. Or RX II if I can get it at a very good price. For street shooting I think Aria is suited best - it's compact, lightweight, non-intimidating. Closest best thing to Leica M.
I really like the viewfinder - it's big and bright. Makes focusing even in bad lighting conditions relatively easy. The LED readout however is done and placed badly - it's not so easy to see at all times.
Flash is a weakest link (but it is so in practically every Contax camera). It can sync only at 1/125sec which means you will almost always get some ambient light into the picture. It's not so bad if you actually want to do that anyway. It's bad if you really wanted to shoot at 1/200 or faster to eliminate all ambient light.
Operation is very straightforward. Built-in meter is about as accurate as it gets with SLR cameras. If you need better accuracy, you need handheld meter.
Aria won't balance too well with heavy lenses. I have 6 lenses and I consider these to be on the heavy side when used with Aria:
Planar 85mm f/1.4
Sonnar 135mm f/2.8
Distagon 35mm f/1.4
However, I rarely use the Sonnar, so that doesn't bother me. When I use Planar 85mm f/1.4, I mostly do portraits and that sort of thing, so that doesn't bother me again, because I hold my camera in such a way that my left hand supports the lens+camera and my right one operates the meter, shutter and exposure compensation. When I use Distagon 35mm f/1.4, I'm usually doing some landscape photography and use tripod, so that doesn't bother me. When I do street photography with Distagon, I do the same thing as with Planar, so again it doesn't bother me. To sum it up - weight balance is an issue, but only if it bothers you
Most of my pictures are taken with Planar 50mm f/1.4 and with Aria it creates a perfectly balanced package.
It seems that slightly less than 30,000 Contax Arias were made and I think it's more than RX.
One thing I sure would have loved to have on this camera is half-stop shutter speed increments in manual mode. But that would probably make it much more expensive.