I have the 70-200 L IS 4.0 one, I love it... but it just doesn't cut it for what I tried it out on:
Why on earth did I even TRYYYY to take pictures, I don't know... but this is what happens when you do.
Indoor soccer
Iso 1600 (as high as my camera would go, perhaps if you had a better iso performance camera, it could work for you)
f 4.0
The results are horrifying, but I had to try it out anyway
http://i28.photobucket.com/albums/c206/chantal7/IMG_7946.jpg
http://i28.photobucket.com/albums/c206/chantal7/IMG_7906.jpg
http://i28.photobucket.com/albums/c206/chantal7/IMG_7919.jpg
http://i28.photobucket.com/albums/c206/chantal7/IMG_7926.jpg
http://i28.photobucket.com/albums/c206/chantal7/IMG_7942.jpg
So what am I saying? I'm saying if you are doing any kind of indoor sports, I advise spending the extra grand on the lower F stop!
One extra stop wouldn't of made the difference, you would need 2 stops minimum (for stopping action and giving a correct exposure)
If you were shooting indoor sports you need a camera that will comfortably sit at 3200iso plus the extra stop on the lens (7d, 1dm4, d700, d3s)
If you are panning side ways to follow action, switch your IS mode to 2.