I'm comparing these two lenses because they are so different. I will be using it as a general purpose telephoto zoom as well as for portraiture. If I chose the 70-300, am I going to regret not having the f/2.8? and if choose the 70-200 am I going to regret the extra reach and the IS? By Image Quality I mean "sharp" images as most zooms outside the "L" range seem to be soft especially racked out.