D600 is suitable for nearly every photo need for nearly every photog.
Yeah, if you alter your shooting style to work around all of the compromises.
The D800 is about $800 more than the D600. I shoot 14 bit lossless compressed RAW, and I get about 200 shots on an 8gb card (41MB avg)
So the file sizes are really a non-issue. Even in the uncrompressed raw (I would assume 75MB/file), storage is cheap and if you are paying 3k for a camera,
the extra $150 for a new 1TB HD shouldn't really matter.
The 1/4000 shutter speed is a big hit for those that shoot @ f/2.8 or wider outside in the sun.
In certain conditions you're going to need that 1/8000.
The flash sync speed is another head scratcher. Weakens strobes by a third.
If video is your thing (I'm just getting into it), the fact that the aperture is controllable DURING a video shoot is huge.
The size of the focus area is what turned me away. I was willing to workaround the other things, but then I saw a demonstration
of the focus in action, I couldn't imagine using it. D800 is smaller than the D7000, but the D600 is sooo tiny. I like to ride the outside of the frame
with my focus points, and the D600 would kill my shooting style completely.
They both take photos, and the outcome is excellent on both sides. However, there are some strong limitations when buying a D600, and if you can live with them,
then I would definitely advise going with the D600. I almost bought it. Sooo close to buying it. But that damn focus area...