Due to Amazon having processed DP1 pre-orders out of sequence, I am unfortunately still without my DP1. Thus living vicariously, I was happy to come across this thread at DPReview, where John Kenny was kind enough to share his 5D and DP1 comparison photos. The 5D was using the 24-105mm f/4L zoom lens at 28mm. Both cameras were set to f/8, ISO 200, on a tripod with self timer. John kindly made his RAW files available for download here.

I processed John's DP1 and 5D RAWs using Sigma Photo Pro 3.1 (Mac) and Capture One 3.7 Pro, respectively. In cases of upsizing, the Genuine Fractals 5 Photoshop plugin was used. I sharpened each photo slightly at the final output size.

Here's the resized scene as taken in by the 5D:



Resized DP1 image:



Here are the full-resolution comparison images:
Canon 5D at native resolution (12MP)
Sigma DP1 upscaled to 12MP
Canon 5D upscaled to 19.4MP (sufficient for 30 x 20 inch print at 180 pixels/inch)
Sigma DP1 upscaled to 19.4MP

For those who'd rather not examine the whole file, here's a comparison of a near-center 100% crop from the native 5D file on the left and an upscaled DP1 file on the right:



I'll let the results speak for themselves with just a few comments about the testing conditions. I personally would have preferred to see an ISO 100 comparison, as I'd expect higher ISOs to favor the 5D (albeit only very slightly at ISO 200). I'd also like to see them shot with the same depth of field (different f-numbers) since the current use of f/8 for both likely hinders 5D corner sharpness (would probably improved with a higher f-number) as well as DP1 overall detail (diffraction-limited at f/8).

Thanks again to John for sharing these. If anyone thinks my processing has misrepresented the capabilities of one or the other cameras, by all means download the RAW files and show us your version.

Addendum: As the following right side crop comparison shows, both the 5D and DP1 files suffer from aliasing effects. The 5D crop shows significant color aliasing as well as luminance moiré, whereas the DP1 crop is dominated by luminance moiré. So much for Foveon sensors not needing an AA filter.



Here is the DP1 crop before resizing, straight out of Sigma Photo Pro with all settings neutral other than custom white balance. As you can see, the moiré is present in the native file and was not introduced by Genuine Fractals.