After reading the reviews, I weighed the tradeoffs and placed an order for this lens. Should be here this week. Will post back here with test shots and comments when it comes in.
I called Sigma to ask a technical question about this lens. It seems that they have put out several versions of the 17-35mm f/2.8-4 lens. I wanted to know if this lens had the HSM hypersonic motor focus drive. Here's where it becomes interesting, from the rep and Sigma's lens page:
[17-35mm F2.8-4 EX DG Aspherical HSM] Sigma, Canon, Nikon (D)
[17-35mm F2.8-4 EX DG Aspherical] Sony/Minolta (D), Pentax
They are making this lens with the HSM built-in for Canon, Nikon, and Sigma-proprietary mounts only. Sony mount only has the drive-pin focus type available. So I ordered one anyhow. By the way, (D) is for distance information, not 'digital;' (this is a property of the mount).
Continuing on we learn that all of these lenses are full-frame, not APS-C (1.5x) crop corrected. So don't loose sight of the fact we're talking about an 25.5-52.5mm apparent focal length here. "26mm at the wide end?" I turned the question over in my mind. Would it be okay? Well when the dollars weighed in I came to grips with the fact that getting a true 17mm apparent, would require a 12mm lens like the Sigma 12-24mm F4.5-5.6 EX DG Aspherical HSM. Those are expensive and not as fast, HSM notwithstanding. As an aside, that is one of those triplicates you should try to avoid in your writing.
I went to a local retailer to test this lens before ordering, however it turns out the version I tested was the Sigma 17-35 F2.8-4 EX Aspherical. Not DG. Ugly as sin. This works fine and has a nice action, but I think the exterior is an eyesore. The old Sigma EX lenses had rubber zoom/focus rings with a "tire tread" type of grip. It looks dumb. The new ones have a simple straight knurl pattern. To further add to the confusion I believe the Dyxum listing has the wrong photo for this (discontinued non-DG lens). I am interested in seeing what comes in the box.
As we know, lens offerings for the A mount are only recently picking up. The Sigma rep on the phone said these things may change in two days, after PMA. I think there's a good possibility they will add HSM to some of the lenses for the Sony/Minolta mount. They might even do it for the 17-35mm. If that happens I'll have to see how much it costs. If I like the "classic" one that comes this week, I may just keep it (depending on the price of a new one).