Sigma 120-300 f/2.8 for highschool FB?

Anyone used this lens to shoot highschool (night) football? I've read a few comments that AF isn't that good at night, fine for daytime. But only a couple of comments. I saw a photographer using one tonight (first game with this lens).
I like the speed, the range, but I don't need slower AF...and the lighting conditions are poor. Currently I'm using 70-200 f/2.8 and 200 f/2.8..and
still having to shoot at 1600 to 3200 ISO.
I would like the longer range. How's the sharpness...wide open..at 300?

Photorebel wrote in post #2148587
Anyone used this lens to shoot highschool (night) football? I've read a few comments that AF isn't that good at night, fine for daytime. But only a couple of comments. I saw a photographer using one tonight (first game with this lens).
I like the speed, the range, but I don't need slower AF...and the lighting conditions are poor. Currently I'm using 70-200 f/2.8 and 200 f/2.8..and
still having to shoot at 1600 to 3200 ISO.
I would like the longer range. How's the sharpness...wide open..at 300?

I have not tried this lens in the conditions you work in but I have used the lens,focus was very fast and it was frety sharp wide open,as I shoot hand held I opted for the canon 300f2.8 and feel the is was worth the extra.