D800 don't suck at high ISO. It's actually the best Nikon camera body for high ISO if you print or view on the LCD screen at same sizes.
The 5DMkIII is only better in terms of noise compared to the D800 when shooting JPG. When shooting RAW, the D800 is better. Again, this is comparisons when printing or viewing on the LCD screen at same sizes.
Could you quantity what "non-fast" and "fast" low light work? You mean fps?
Yes, the D700 still has it's place as an
affordable FX that shoots relatively fast with a battery grip.
But comparing noise levels between the D700 and D800, I'm afraid the D700 (and to a certain extent the D3s) will loose out badly.
A used D3s only if you're using it for sports. If it's just lowlight you're looking for, the D800 is still better.
If you can just trade the fast fps you get on the D3s with the amount of dynamic range, cropability and quality of pixels you can get from the D800, it's worth it I think.
Yup, focusing on the D800 is the same as used on D4 and the D4 (as well as D800) has faster and more accurate focusing especially in low light (down to -2EV) than the D3s.
I wish I have the D800E also.
Oh my....

How much did it set you back?
What are you going to use it on?
How you know he's going for the Super Gt 2012?
For better high ISO, the D800 is the one !
But then again if you predominantly shoot sports, the D4 makes more sense. Oh, the upgrade to D4 from D3s should not be for the very slightly better high ISO performance. It should be more for the better focusing performance and for the added new features.
He will be there... haha 2010, 2011 and now 2012. Except this time I'll be inside track too xD
Hahaa wanted to.. but see he is busying so nvm.
can spot him next time
seriously go plug ur mem card to that cam and borrow for test shots

I will xD... try the video feature too LOL. Let's see how it goes.