This seems like a great camera at an excellent price. However, when I add up the cost of camera body, battery grip, new RRS L-brackets, and at least a couple of FX lenses, it just doesn't make economic sense to me. To say nothing of the loss I'd take on my D7000, accessories and pro DX lenses if I chose to sell them.
Any working pro or semi-pro will have to agree that you need a quality back-up body (especially if you shoot events) and there's no way I could drop over $4K for two D600 bodies.
After seeing Nikon's quality control problems with the D800, I'd advise waiting at least 6-8 months to buy a D600. There's no sense in being on the bleeding edge of technology if you have issues with the equipment.
I've been more than happy with my DX bodies and lenses. They've produced excellent images for me and my clients. While I won't be adding any more DX lenses to my kit, I may just drop a grand on another D7000 body, or wait until the D400 or D8000 comes along.
To those of you that are buying the D600 now, thanks for beta-testing it for rest of us!