SLOW focus on the Sigma non OS version is not like mud... It's slower than a HSM, but it's definitely do-able for sports. Will you have some missed focus? Probably, but not more missed than you hit spot on. I shoot with another Mom who shoots football with the non OS version and she loves it. Her images turn out beautifully with it. She wishes she had the newer version, but it's not holding her back either.
-I also have the Tamron 70-200 f/2.8. Now that one focuses SLOW. I have used it for sports and I could feel a pinch with it. For macro, wedding and portrait work? Absolutely beautiful lens for the $.
I have the non-OS version. It's still an HSM lens, and focuses like one.
To the OP, I've had the exact lens you're talking about for two years, and I've taken over 50,000 sports photos with it. It's held up well for an $800 lens, that's for sure. Just some minor rub marks and a few chips in the tripod foot. And I've beat the heck out of it.
Let's start with the downsides of it: It's slightly soft at 2.8. Still useable, but you'll wanna keep it at 3.5 or higher when possible. It's also slightly soft from 180-200mm, but you really have to look close to notice it. Definitely not a deal breaker, especially for the price of the lens. Depending on what body you use, you may get some focus hunt in low light. I experienced it on my old D40, but haven't had any issues with my D80.
The positives: It focuses pretty dang fast. Not as fast as my friends Nikkor 70-200 VR, but far closer to it than I'd expect for the price. It's tack sharp beyond f/3.5m and under 180mm. I can honestly say I've never felt that not having the nikon version has held me back one bit.
Here's one shot that I took recently:
160mm, f3.5, 1/1600th, iso 200.
And a crop: (I was using the center focus point, so it fell on his midsection rather than his face. I should have been shooting at f/4 or 4.5 for the greater DOF.
For more examples from this lens, check out the sports galleries on my website (
Destin Danser Photography -- Western -- NY -- Portraits -- Sports). All of the football and soccer photos were taken with it, as were about 80% of the motocross photos.