D800: what's the point?

You should not buy either D800 model if you don't have enough insight to distinguish between their individual qualities. Soft images? Practice raw image processing and you will learn that sharp is a better word. Noisy in hi-ISO? If you want lower noise, the D600 is better (as you have shown). The D800 models fare equal regarding noise. So in essence, the D600 is better if you want FX format, if you want DX format the K5IIs is good.