I was just thinking. If the D800 upgrade has around 50MP which is not entirely impossible and gives the ability to shoot fast with a DX crop mode ?7-8 frames/ sec than the D300s upgrade will definitely be dead. You will essentially have pro DX and FX in this body. When shooting wildlife use DX crop mode and fire away otherwise get amazing detail in studio/ landscape work.
"Cameras and lenses are simply tools to place our unique vision on film. Concentrate on equipment and you'll take technically good photographs. Concentrate on seeing the light's magic colors and your images will stir the soul." Jack Dykinga