There is much I want to say about the questions raised in your last post but I do not have the time this morning because I am going to hunt down a nesting Prothonotary Warbler this morning and shoot it like a dog . (I hope, if my friend is right). I want to ask you one question, and your answer will help me frame an answer to the other issues.
The numbers above are the DXO numbers for each camera. Please explain to me, in the context of DXO's protocol, exactly what is the significance of ISO 2853 to the D800. And please explain to me exactly what happens at ISO 2854 (or really, say ISO 3200). Similarly what happens when the D3s ISO is boosted above ISO 3253.