"I wonder how many of those who rushed to pre-order the D800 and sold their D700, now may be thinking if it was such a great idea "
This is the rule of wing walking as well. Don't let go of what you've got until you've got hold of something else!
The morning after D800s started being delivered (with all the humorous "box openings") I checked out both of my D700 cameras and both were still making the amazing images they did the day before! And BTW, I sold my D200 about two months after my first D700 arrived and was thoroughly wrung out.