High ISO of D800 still amazes me as does the whole Nikon system

I don't see the posterization you can see in these images.

It is definitely visible and I am actually even using the same lenses I used on the D300s, so we can't blame the lens for the increased detail.

Yes, it is fair to say that lower ISO is better even on the D800, but comparing them your way is not what I'd call fair test since you could not take the same image with an equivalent lens at that low ISO due to the fact that the shutter speed would end up far too low. Even 1 stop from ISO6400 to ISO3200 is too much but two stops below that would make it totally impossible, so no, it would not be fair to compare that way at all.

Fine, I am not trying to convince you. Wait for the D400 if you still believe in it, maybe I'd do that as well if I were you. Never the less, I don't think that what I see is just fairy dust, technically it is fairly easy to show with two identical images and I actually did that more than once, though I would not start a mud throwing fight for it.