I have used an 80-200 2.8 of the same era often for D1 college level hockey. To a degree, if you're really good at positioning the focus sensor on the player and keeping it there despite their erratic motion, you can compensate for the slower AF. I've never been able to do that too well thus far. You really have to get into their mind to do it. But due to the plexiglas and reflections, it's really hard to use such a lens and get a lot of in-focus frames. I get maybe 1 good shot out of every hundred, and most are out of focus either just a bit, or drastically (usually drastically is my fault for not keeping the sensor lined up with the player). If you didn't have to shoot through glass, it might not be as bad as far as focus (but worse for personal injury). I don't know about the 300mm though, my reference point is the 80-200. I don't know which is faster. But the 80-200 is quite slow and has a lot of friction/drag to it. As far as I'm concerned, hockey is the hardest sport to shoot, period. You should set lock-on to either medium, most likely...fast will create more hunting. Also keep your thumb on the AF lock button and be ready to hit it. These lenses also have a focus range limiter that helps. Only use center AF point.