I am looking for one of these zooms. I have a chance to get the old one used at half price of new, so that is a factor. I read a review of the version 2 and they suggested the V1 might be a little better optically. Is that true? I know the V2 focusses faster. Am I going to lose much in picture quality if I stick with the version 1 of this lens? I am using it on a 90D camera. Anyone else do this comparison? I want to stick with a full frame lens, so I can use it on my film cameras too. And possibly mirrorless cameras down the road too. My other option is the Tamron 70-300 SP lens. What say you?