Thanks for posting this. I have been considering adding a D400 for wildlife and air show photography. I think it would make a great addition to my stable. I currently use a D3 mainly for sports, and a D800 for landscapes, portraits, and travel. Neither is optimum for wildlife or air shows, and I suspect the D400 will be lighter and better for travel as well.
I still have a D200 and pro DX lenses, so all I will need is the D400 body.