I bought the D800 as I was tired of waiting for the D300 replacement. This decision is forcing me to replace my Sigma 100 - 300 F4 with the 120 - 300 2.8. I have the Nikon 70-200 f2.8 but the reach isn't enough and while you can crop more due to the high megapixel count, you really can't see what you are doing when shooting.
I thought I might use this camera for 6 months to a year, sell it and obtain a D400. Now I'm not so sure.