I'll pitch in here, as I've used my DP2M for a couple months now, and had the opportunity to take some test shots with the RX1 just before New Year's. Nothing, except other Sigmas, is as slow as the DP2M, and I mean by a lot. Achieving focus isn't the problem; it is writing to card. In taking some panoramic shots, I think I hit the buffer at nine shots, then couldn't take one more until the buffer had cleared room for it. And, believe me, that is a considerable wait. Also, I think I can't change camera settings until everything has been written to card. That is another perplexing wait. On the other hand, it has been my recent favorite camera for outdoor shooting. When you nail the focus in good light, nothing looks as good -- actually spectacular onscreen and in print -- including files from a full-frame DSLR.
You asked for a comparison with the Fuji X100. I don't have one, but picked up my daughter's X100 about a year ago. I had expected to like it, but didn't. She gets nice photos with it, which I download and print from full-size files off of our Flickr accounts. But for whatever reason, it didn't feel good in the hand, and the controls just didn't seem natural or comfortable to me. It could be I was just accustomed to the controls on my GH-2, and the differences seemed awkward to me. As soon as I picked up the camera, I wanted to put it down. I am hard-put for an explanation, but I think it goes to show how much that immediate in-hand reaction to a camera can mean. On the other hand, as soon as I picked up the Sony RX1 in the camera store, and took it out on the street for some test shots, I wanted to cradle it in my hand forever. Maybe that is a slight exaggeration. No -- it really felt that good. And the controls certainly added to the feeling. With the aperture control physically turned on the lens, and facing you when you look down, and the exposure compensation on a nice large dial on the top right of the camera, you don't have to look at an LCD or EVF to confirm or change your settings (or think about which buttons or dials to press or turn to change them). I have in fact made a decision to get back to my camera dealer in the next few days and buy this camera. I expect to use auto-ISO, especially after reading about Michael's experience with it, and then not have to confirm or change that setting either. I also will put a Voigtlander viewfinder on the camera, as I did with my DP2M. The feeling of quality in the build of the camera is major.
The first night I worked with the test files from the RX1, I hadn't realized that Adobe had updated Camera Raw to deal with them, so I processed the jpgs, the results of which would have kept me from getting this camera, at least from a file shot in gray afternoon light at ISO 1250. Lower-ISO jpgs looked much better. Then I finally updated Photoshop last night and processed that same image
from the raw file. Very fine. For years now, I have worked only from raws. I expect this camera will make all my shooting at its focal length a real pleasure. --Barbara