Upload & Sell: Off
I haven't used any and thinking in the near future to get one, but is the D3s really far far ahead in high ISO performance?
Yes. Its D4 level. Even ISO 800 is cleaner or as clean as some mirrorless are on base ISO. Per-pixel its camera with best SNR so far. D4 is actually slightly worse, but it has native ISO 100 and better DR, so its probably over-all better camera, just that difference isnt huge by any stretch.. D4 is (apart from controls, ergonomics) just a small evolution of D3s.
And as it was mentioned, it has rather nice colors.. (actually one of few that I can like from Nikon, reminded me bit of D3x, probably similar or same color matrix).