So, today I got down to details. I made prints of the most comparable shots I took with the 1Ds3 and D800E, in what I'd call plausible landscape conditions: ISO 100, f/11. And I made some prints. I had a few printer problems along the way (paper feed, weird.) But in the end I made three pairs of 15x10 prints to compare sharpness.
- Full-frame: This works out to about 491 ppi for the D800E, 374 ppi for the Canon 1Ds3. I didn't expect to see tangible differences here, and I didn't.
- Big print enlargement: Here I printed out sections of the print correspoding more or less to printing the whole image at about 26x17.5". (277 ppi Nikon, 214 ppi Canon). Here, I expected I would see some difference, and there is just enough difference that I can reliably pick out the Nikon image from the Canon blind. It's not a huge difference, but there are prints of mine for which there would be a quality difference as a result of using one camera or another.
- Larger print enlargement: Here I printed out sections of the print corresponding more or less to printing the whole image at 45x30". (164 ppi Nikon, 126 ppi Canon). Here I expected I would see a large difference, as I'm used to thinking of 150 ppi as a "magic breakpoint" in image quality. For my eyes, I'd say differences were apparent but not large, but in some places in the image, particularly some tree bark, the difference in microcontrast was signficant at viewing distances up to about 36".
In short, the answer to one of my two big gear test questions is answered. The answer was, for print sizes I make, and for shooting conditions and settings that are plausible for my work, does the Nikon D800E beat the Canon 1Ds3? Can you see it in prints? Yeah, you can. Probably not small prints, prints less than 15" on the long side.
This is more or less what my usual rules of thumb would have told me, but it's nice to see the theory applies to real life.