I did not see a big difference in sharpness between the 2 Tokina's. The 11-16 maybe little sharper at wider appertures, but stopped down, where I use my 12-24 most of the time, I did not notice an obvious difference.Very interesting suggestion. I've been toying with the idea of the 12-24 but had been put off by 12mm at the wide end. 10mm to 11mm isn't such a big jump, from 10mm to 12mm is noticeably tighter. I hear nothing but good things about the 12-24 though. How does it compare in sharpness to the 11-16? It's supposed to be built like a tank too, which can only be a good thing.So went for the Tokina 12-24 II : slightly larger focal range than the 11-16, sharper and cheaper than the 10-22 and I do not mind it's slower max aperture.
This will not make it easier, but at these focal length every mm counts. 10mm is a lot "more" then 12mm. I find 12mm wide enough for me and the 12-24 leaves no gap towards my 24-105. Maybe for you the 11-16 is a better choice.