There are photographers who have to use high ISOs. Some even start at ISO 6400 and increase from there (concert photographers)Why is everyone talking about high iso? For me it is never found D700 high iso a problem. If the D800 is better, even by a little bit, it is good enough for me.
I only need like ISO3200 the most.
What I sometimes find lacking in the D700 is
1) lack of video
2) not enough DR
3) AF can always be better as there are always missed focus shots.
I think the D800 improved on everyone of them