i'm in the market for a 70-200. I am firmilliar with the whole line-up of canon 70-200s and i'm trying to make a decision. it's probably going to be the f4 becuse it is cheap, light, sharp, and worth every penny. i've shot with all but the 2.8 IS and noticed not much difference between the f4 and the f4 IS. I could probably afford an inexpencive used 2.8 or f4 IS if the right deal came along... but i'm wondering what everyone else thinks of their 70-200 which do you have,do you like it, do you wish you got a model up from yours? or even wish you got a lower model? what do you like and dislike about it?