@ebiggs1 wrote:"Is the couple hundred dollar jump used worth it from the f/4 to f/2.8 L IS?"
To answer that question, IMHO, it is. I have owned the f4 version and the f2.8 both IS models. The f2.8 is in every way the better lens choice. I sold my 70-200mm f4L with one of the 7D's I owned. That person is happy with the combo, so there you are.
I can't disagree. I have no experience with the f/4 models; but I've used two copies of the f/2.8L IS II: one at work and the other I bought for myself when I retired. And I know of no lens that does a better job for its intended purpose. It even handles a 1.4x III teleconverter remarkably well (which probably can't be said for the f/4 versions).
I understand that there is an even better (smaller and lighter) version of the f/2.8 on the horizon, but you have to buy an R5 to use it effectively. Which is a subject for another thread. 
