Well, I talked myself out of the 300mm F2.8 L IS, if for no other reason than the fear of walking around with a $4,000 lens on my camera. I decided to go with the 300mm F4L IS instead. I rented the F4L IS version a few weeks ago and was completely satisfied with it.
But, it is becoming obvious that I need a slightly faster lens for soccer at dusk/under lights. I thought about the 70-200mm F2.8L IS but have found many posts stating that the IQ is at the bottom of the 70-200mm family. If I spent $1,700 on that lens I would probably sell my 70-200mm F4L IS, which I am not sure I want to do.
So, I am thinking about the 70-200mm F2.8L non-IS or the 200mm F2.8L. I shoot kids soccer from the sideline so focal length is not a big issue. I figure at 200mm, I will not be zooming out so that is why I thought about the 200mm F2.8L prime. Is the AF fast enough for sports on the 200mm prime? Would I be better off with the 70-200mm F2.8L non-IS or selling my F4L IS and getting the F2.8L IS?
I realize that it is ultimately my decision but I am interested in other thoughts.
Thanks.

Believe me the 300 f2.8 IS is 
