Upload & Sell: Off
Well, I own the Nikon f/2.8 VR II model for my D800 and it is fabulous but am selling it because I will get the new, much smaller/lighter f/4 model. (I shoot mostly events and need to walk around a lot with my equipment and the f/2.8 lens is too heavy.)
I just listed it on the buy and sell board this morning. $1900, 9+ condition with box, etc.
I have not seen any test reports on the f/4 model since it is too new, but I know Nikon lenses and am convinced it will be excellent. That's what I will buy.
DP Review has started working with it: http://www.dpreview.com/news/2012/12/05/nikkor-70-200mm-f4-samples-gallery
I have tested the Sigma and did not think it felt cheap. In fact, I would be happy with that lens if it were not so large/heavy ... although it's not as impressive as the Nikon f/2.8 lens (but also less expensive):