"Anyone on here thinking of swapping the 2.8 for the new f4?"
Short answer - nope. The 70-200 f/2.8 is perfect for my purposes, the weight is not a problem, and I just have no incentive or desire to swap. However, I fully recognize that others will have good reasons to do so. We all have our own "style" and photographic goals and should select the tools that best fit our needs.