Torn, 1D MKIII and UWA. Canon 10-22 or Tokina 11-16?

Why not a sigma 12-24 that is actually made for full frame?

Thanks, guys.

I think I'd be affected by the gap betwwen the 16-28mm range if I go with the Tokina.
However, that lens seems to be the consensus... I'll sit on it for a while.

Not sure I want to deal with Sigma's screwy Quality Control between their lenses.

Have you considered the Sigma 10-20?

I used one of those on a 1D3 for 18 months and it's great. Sure it vignettes badly at 10 and 11mm like the Canon, but as a 12-20mm lens on a 1.3x crop it is fantastic. It also seems to be one Sigma lens that doesn't have many quality control issues - pretty much everyone gets a good copy. And a good copy really is great. I've never been left frustrated wishing I bought the Canon 10-22 instead (and I know the 10-22 is a great lens).
No mods necessary, no chance of it hitting the mirror, and you'll end up with change in your pocket after swapping your Canon 10-22 for one.

I was also very tempted by the Sigma 12-24mm as a UWA for my 1D3 and 5D2, but after checking it out in the shop on my 1D3 I was extremely disappointed with IQ. The copy I tried was terrible, and it seems that unlike the 10-20, this lens is very hit-and-miss, with more bad copies out there than good.

I did, but I'm limiting my choices between the 10-22 modded or the 11-16. If i'm going to sell the Canon, I better be able to let more light into the lens in return. I love my 10-22, and it would hurt to sell it with a compromise.