The prints Canon had on display were absolutely
stunning! They worked on all levels of Canon's
marketing genius: Cameras, lenses, and printers.

I had a great time comparing some smaller prints
(I think 20x30) from the 40D/1DMKIII/1DSMKII.

The friendly Canon rep had a good eye. Two very similar
prints of the same model. I told him the 1DIII print would be
spectacular on its own, if it weren't side by side with the 1DSMKII.
We both saw the resolution difference, particularly in the eyelashes,
the resolution on the skin pores, and the 'crow's feet' area of the eyes.

Again, the 40D/1DIII prints were fantastic on their own.
Don't make yourself sick by comparing images to a 1Ds series
body :-)