Sigma 24-70 f2.8?? i think is your only option.
just got myself the tamron 28-75mm, not had chance to test it out but will over the weekend.
most people on here rate it highly though
17-40 L is a good lens *** used in the right circumstances on a 5d, it suffers a little distortion at the wide end when close ish to the subject but i suppose thats expected. I sold my 17-40 to part fund the 24-70 L and tbh, i've not looked back.
I'm not bothered about the IS, thats just something to fail outside the warranty and imho encourages poor technique.
I had one and found it to flare a lot, though it was admittedly in conditions were flare is likely (no UV or other filter to blame)
I currently have only a 28-135 on my 5D2 and it hasn't bothered me having only 28mm to play with...ok i'm looking for a wider lens just now, but the 17-30 range on a FF is a different kettle of fish.
A quick search of Google will show plenty of opinions and reviews.
There was two version of the sigma, the only difference appart from price was HSM motor.
did you end up selling it? if so, what did you replace it?
I'm not bothered about the IS, thats just something to fail outside the warranty and imho encourages poor technique.