Hey i love my 17-40/5D.
But i was warned about these things before i bought them, and its stuff that can be adjusted and tweaked and compensated for.
Distortion is something you can easily work into a composition like his shots show, but its still there, if you look at the barn for example. Sometimes it can actually make the shot better, as for vignetting, its worse depending on your filter, but even then you can adjust it after on the computer.
Its just something that i was pleased to be warned about so i pass it on
I wouldn't know about the 16-35, sorry.