Jump from D80 to D600/700/800???

I recently made the same jump from the D70 (also with my trusty sigma 24-70) and ended up getting the D800. I could not be happier with it. It is indeed "robust" and the amount of detail and dynamic range compared to my D70 is almost obscene. I cannot speak for the D600 and D700 but they both seem very good, although I probably would not invest in a camera that is already 5 years old (but that's just me).

Long story short; You cant go wrong with any of them. You have read the reviews and only you can determine what features are more important to you.

Good Luck!