I've got such a big mouth...
To counter that tunnel-visioned, apoplectic test page with a dose of reality, here is a screen grab of an 11" high crop of a 43 inch high x 96 wide image I am printing right this minute. A stitch with a single 5D2 vertical frame, and a few more left and right. This part of the frame is in deep shade. It's gorgeous, Crewdson would cry.
Please note the 50% down at the lower left corner. At pixel level what you see here is a little bigger than print size, but half the resolution. It takes smooth paper to show anywhere near the full resolution on a print. Not bad for a "crappy" 5D2 frame and a wee bit careful post processing. And BTW this is from a corner of the frame, not the center. Focus is everything, zooms stink, and so does autofocus. Mama don't take my 55mm Micro Nikkor away, or even my 45mm T/S lens, or my manual focusing ring.
Be sure to look at this all the way scaled up.