I started this thread long ago. I really like Zeiss glass and decided to stay with manual focus, so I dabbled in Contax gear. Here is what I found:
Aria: I got a few rolls through the camera before the electronics got confused and I don't know how to fix it. It won't detect DX and I can't set EI/ISO. The controls that do so will only bring up the custom functions. The camera is light and viewfinder bright. The size reminds me of the OMs. Didn't use enough to really say much.
RX: Solid and smooth. The focus confirmation is useful from time to time. The camera is heavy, but comfortable to use.
RTS III: Heavy, smooth, large bright viewfinder, vertical shutter release and.. well.. it doesn't work. Mirror hangs, metering was questionable and so I didn't use it much. A few weeks ago I sent it to Tocad and they sent it to Japan for repair and CLA. I received a message saying that it would cost $230 to repair... reasonable. I paid the bill, so I'm guessing that I'll have it back within a month. I look forward to getting this one back. I think that this will be my favorite of the bunch.
LENSES:
Zeiss 100-300mm .. Great lens. Using it for Soccer. Have adapter for NEX-7
Zeiss 100mm Makro .. One of the sharpest lenses that I have ever used. Expensive... I found one NIB and wow .. what a lens.
Zeiss 50mm Planar .. enough said.
Zeiss 45mm Tessar .. The weak lens of the bunch, but right size for Aria
I also have two Contax flashes. One is from my G2 kit and the other is their larger hotshoe mount flash. Both flashes work as advertised.
The best advice above was to stay with Canon, but I've a weakness for lenses that have aperture rings, even the old Canon ones. I just picked up a canon zoom for shooting NEX-7 soccer video.