Hannya wrote in post #18786376
As I understand it, IS is really intended for when hand-holding at low shutter speed (for guidance, a shutter speed less than the focal length - e.g. 200mm lens, less than 1/200th shutter speed) so highly unlikely to ever be needed for sports unless you are playing around with arty movement type images. I've used the horizontal one for panning motor sports, but realistically virtually never used it at all!
As I understand it, IS is really intended for when hand-holding at low shutter speed (for guidance, a shutter speed less than the focal length - e.g. 200mm lens, less than 1/200th shutter speed) so highly unlikely to ever be needed for sports unless you are playing around with arty movement type images. I've used the horizontal one for panning motor sports, but realistically virtually never used it at all!
As you say that's a guidence and not a rule.. in reality I am not so sure... sit in a field under 3g schoo, floodlights with a gale force wind blowing your 400mm about and try to get a good shot with a 400 shutter speed... As mentioned IS wont slow your focus.. what it slows is the aquire of focus.. so in poor light for such things as corners it can help.. manager/bench shots .... I certainly wouldn't reccomend using IS on a normal day shooting sports.. But in extreme (bad) conditions why not use it for that extra help? 
