Great question and exactly the conundrum with which I am currently faced. I pre-ordered the 70-200 f4 and it is now in and ready for pick up. I only recently purchased the 70-200 f2.8, and as others have said, it is a beast. When I had it on my D800 and walked around a bit, it really weighed me down to the point of hurting my shoulders. That said, it is a fabulous lens, so I am stuck trying to figure out whether to keep the f2.8 or sell it. The answers to your post suggest no clear consensus.