I'm in the same situation as K2 Guy. I have a D7000 and a D600. The D600 is providing low light shots I wouldn't get with my D7000.
Having both these cameras is like doubling the number of my lens. I have a 24 - 70mm f2.8 (FX). When it's on my D7000 it provides a 36 - 105mm equivalent. If I need wider low end, I put the lens on my D600.
If I need more reach, I put my 70 - 200mm f2.8 (FX) on my D7000. If I'm doing closer portrait work, I put it on my D600.
The combo give me a lot of shooting flexibility. You could do the same with your D200 and a D600.
If you get the D600 or the D7100 you'll be very happy. There are no losers in that crowd!
"Red is gray and yellow white, but we decide which is right ....and which is an illusion"