It's good that you're testing so, wallstreetoneil, since prior to the 5DS release some people had expressed concerns about whether current lenses would be able to produce enough resolution for the camera's small pixels. Another concern was more internal noise.
Regarding apertures, well, it looks like just another one of those 'we'll fight to the death about this' topics, not unlike using clear filters for protection on lenses; no matter what the minimum aperture of the lens is (f/22 or f/32) some people's minds smallest aperture will be locked at f/11 and to stop further down equals to anathema of cosmic proportions—diffraction being the horrid monster causing this nigh irrational fear. They'd rather spend hours in front of the computer performing exposure blending and masking away than simply turn the dial ~3 clicks more.
I regularly shoot at f/16 and even f/22, with wide angle lenses. Yes, at the latter aperture the image does get a mite soft, but adding a little microcontrast compensates for that well enough. At the size the images will be displayed on the Web (and they'll be low res images anyway) the effects of the dreaded diffraction will be negligible and practically unnoticeable. Were I to print the high resolution images large, same thing: the client isn't likely to press his nose to the masonite and/or take a magnifying glass to look for 'softness'—nay, he's gonna stand back and take in the whole picture.
That being said, diffraction (and by this I understand diffraction that is so excessive as to be noted without pixel-peeping) was one of the preoccupations voiced about the 5DS: http://www.photigy.com …hat-to-expect-new-camera/
Based on your tests, what can you tell us about those concerns, wallstreetoneil?