The 16-35II is my most used lens by a lot, I too would add to the ranks to be much happier with a 16-35III than a 16-35IS. I don't need this lens to be much wider than it is (although 14-24 is fine). I really want it to have much better sharpness than it currently does.
Convincing words here. That's why I go 16-35 on the 5D3. Have the 10-22 with my old 30D and that was a very fine lens as the crop equivalent to it. Although it is not that fast.