Nikon D600: Are the "benefits" of this camera really worth it over the Canon 6D?

I think the 5d3 is an upgrade to what you have now, the 6d is a rebel FF and is a downgrade to the 7d and I think that is why a lot of current Canon owners are disappointed with the camera, it does not compete with the d600. But the 5d3 is a great camera to upgrade to so I think you will be happy.

Even if you decided on the lesser expensive cameras I don't think it would be smart to change brands with the gear you have not, there is not enough feature differences between the 6d and the d600 to justify selling everything at a loss. Good luck to you.