I know that this type of comparison is always open to interpretation but sometimes it just presents itself. I planted some flowers a week ago and photographed them with the DP-1. I liked the results very much.
Then I decided to test the upsizing methods at my disposal, Aperture, CS-3 and the printing program Qimage. I cropped the images and upsized to 600 DPI tiff's. I found that both Aperture and Qimage produced very similar images and that each was superior to the CS-3 image. I am certain that there are other ways to work CS-3 and that this was a quick trial. However, the job was easiest in Aperture and there's something to say about easy if it produces great results.
Then today I was looking at the same plant and had my Nikon D-80 in hand. I dialed in the same settings as the DP-1 shot (focal length, f stop, iso, white balance). I noticed that the shutter speed was faster on the Nikon shot (1/125 vs 1/80) so it must have been brighter today. The colors are different. I guess the flower didn't like being transplanted too much. I think it will recover though.
The Nikon image, (upsized to 600 DPI) is quite good technically. The DP-1 image though is great. I guess the color change impacts that somehow. Blue more crisp than red? But! Reviewers of the DP-1 are all in lockstep in chiding Sigma for claiming 14mp from their 4.6mp chip. I would expect the DP-1 image to be running as fast as it can to keep up with the supburb 10mp Nikon image, not the other way around. Any way I look at it, the results of this test go to Sigma.