You can always check on the used sites like KEH.com or Amazon for a version 1 and save yourself $500 to $1000. I also have heard that the newer versions of the Sigma and Tamron are nice lenses. I agree with all of the others that the IS doesn't make much difference in the action grabbing portion of shooting, but I have a differing opinion on the matter. I have the f/4 IS version of this lens and I use it for youth soccer and other things. I usually have the shutter speed at what it needs to be and don't need to worry about the IS, but I am usually outside. One thing I will say is that IS provides a steady to my shot. I believe Bryan has mentioned this in his reviews, but IS not only stops camera shake but it also helps to steady the viewfinder. I really appreciate the IS for that more that than anything. I tend to not have the steadiest hand so following the subject and keeping it in the viewfinder is a big plus.