not a very good comparison to me. would be much fairer if you compared the sigma with lens like 17-85mm or some lens of about the same price. comparing kit lens (<$100) with 17-70 ($600) and 10-22 is a no no for me. they doesn't match in terms of price and focal length.
but its nice to see how to lens perform without any comparing with other lens :thumbsup:
Through what I have tested at 17mm F4, sigma 17-70mm is the sharpest and second is the canon 10-22mm, the last is the kit lens. Whereas 17mm at F5.6 & F8.0, I can't differentiate visually any difference between 3 lens at 100% crop. I am very lucky to have a sharp kit lens but a pity that its too short for me. Though is not very fair to compare this three lens because of its different catergory, however I wanted to say that sigma 17-70mm has a very good quality in sharpness. Then again my kit lens isn't bad too.