Trying to decide if the Canon 10-22mm is worth the $200 premium ($479 vs. $649+$33 for the hood) over the Sigma 10-20mm f/4-5.6. It looks like I gain a third-stop on the wide end and 2/3 of a stop on the long end... neither of which is terribly important to me.

The current lens lineup is 17-55/2.8IS, 70-200/2.8L IS, 24/1.8 (Sigma), 50/1.4 (Canon), 85/1.8.

I have no real problem with Sigma lenses, so the brand isn't terribly important to me... I just want to know if I'm missing something here. The lens will be used on a 7D and it'll be used about 60/40 still/video.

I'm not hot on the Tokina 11-16mm due to the limited zoom range and flare problems.

Why not the 8-16... extra wide angle and less overlap with your 17-55?

When your looking at uwa's don't discount tokina . Both the 12-24 and 11-16 are fine lenses.
The 11-16 would go very well with your 17-55 being 2.8

As ilia said also think about the 8-16 . That 2mm extra from 10 is a huge difference in FOV . And you can never have too wide

I'd honestly prefer a bit of overlap. It helps with not having to change lenses all the time. And while I agree the 11-16 was very sharp, both it and the 12-24 are terrible with flare... and since you can't do a lot of post-processing on video, I'd prefer a lens that wasn't prone to flaring badly.

Then I would go with the 10-22

Its better corrected , handles flare very well and while it costs more now will hold its value very well indeed.

If your prices are correct then it looks like sigma want to much for it. I thought they were knocking the old variable fstop lens out cheap and selling the constant 3.5 a little bit under the canon

My friend is using it on his T1i/T2i. Great lens. Here are few samples (with lens flares):