On the Wallaman falls shots
Look at the coordinates 2 and 5/8" across, 3 and 3/4" down. There is a group of light green lines, possibly grasses, that sweep down to the left on the 40D. On the 5D it looks like 1 line with the rest smeared.
I was at a disadvantage when assessing these comparison shots initially, which I'd created on a laptop in the motel room.
On my monitor back home, there seems no doubt that the 40D crops at both F16 and F22 look better. One might have difficulty identifying a specific iota of detail that's visible on the 40D shot but not visible on the 5D shot, but the over all impression is one of finer grain and greater realism in the 40D crops.
If I were travelling with a 24mp full frame and the 5D as back-up, I can't see myself choosing the 5D for a particular shot on the grounds that at F16 or F22, using the 24mp camera would provide no additional image quality benefit.