if you need movie capability - go ahead it's a big leap forward to have a d600 in terms of features.
if you don't then that probably is just for the sake of upgrading. I won't say no to it, in fact I will say go ahead! Always remember that you should keep a spare money incase of emergencies. Also, if you are very careful user. Even if you travel around the world dragging your d600, you can still sell it for more than 70% incase of emergencies. Our brothers here in CS are willing to buy that for the right price...
It's not a total loss in anyway, that is because you are holding a NIKON