I have a D700 and I'm very happy with it. I have not yet had a situation where I have needed more than ISO 6400. That is not to say that there may not be in the future.
Using the dark frame is also a very good way to minimise this issue.
Using the highest ISO, is like turning your Hi-Fi up all the way, there is bound to be distortion, and of course, nobody has suggested that you are crazy.
>"Back to your high ISO problem, do you have a problem at regular high ISO of 6400, that is really the max ISO for the D700?"<
The fact that this pattern shows up when you are set to ISO 6400 may indicate an issue. If you are really concerned, take your camera to Nikon and have them check it out for you.
I took a picture at highest ISO with the lens cap on, and got quite a bit of reddish noise. Most of which went away at about 80% noise reduction in Lightroom 3. What I was left with, was a band of red/maroon at the bottom of my frame stretching about 10% the way up the picture.
I exported the file and I am unable to see any noise in the final product. For some reason, I have been unable to upload either of these pictures.