I want a DX for the narrow field of view with a full viewfinder image.
While it is true that you can crop a D800 image to the DX size and still have the pixel density of a D7000 â your subject inside that DX crop area will apparel quite small in the viewfinder of the FX body. A DX body magnifies the narrower angle of view to fill the viewfinder.
I shoot a lot of birds â I have a 400/2.8 and all three TCâs giving me up to 800mm and when shooting on a DX camera I still need to crop most small bird images. Using a high mega pixel FX body, with the same lenses, would make it more difficult to observe the birds through the viewfinder.