Sigma 17-70 for landscapes?

I am considering this lens (Sigma 17-70 f/2.8-4.5) since it is light and with a useful range. It seems ideal to take hiking for those reasons.

Has anyone any experience in using this for landscape shooting? I've seen plenty of decent pics at shorter range, and the colour/contrast looks good, but I was wondering how sharp it was near infinity focus? I need a lens that is sharp across the frame once stopped down to f/5.6 or even f/8. I know that lenses like the Sigma 18-50 and Tamron 17-50 are good, but if the 17-70 is equally good at the edges once stopped down then I'd prefer it for the greater range.

If the performance at long range is as good as at normal distances (and I've had some lenses that are not), I'd have no hesitation in getting it.
TIA

I have the 17-70 and it is certainly adequate for landscape. Optically my comparison shows that the corners are soft until about f8 or so comparatively to the shorter EF17-40L or the Tamron 17-50 f2.8. In the center, there are not much difference, but the Sigma do have sometimes focus problems at 17-24mm in low light. The Canon focus is perfect, the tamron focus is also better, but somewhat worse than the 17-40 for focus accuracy.

I decided to sell of the Sigma 17-70 due to the focus accuracy issue and get the Tamron instead. I almost sold my 17-40 but felt its built quality, its optical quality is excellent and decided to keep it.

They sound like problems I could live with. Thanks