I think you won't be disappointed. The D800 is a pretty complete and professionally designed camera. For the u1 and u2 modes, the D800 has four Custom Settings Banks in which you can define sets of settings. I'm not sure if and how this is possible, but you might want to check in the manual whether you can assign opening one or two of these banks to buttons on the camera?
Regarding the sensor contamination issue of the D600, I was and still am one of those who purchased the D600 knowing about the issues, fully prepared to clean the sensor more frequently than with other cameras. But it happened to me that I cleaned the sensor and 10 exposures later there was another dark blob in an image, and that was just too much.
If I could have waited a couple of hundred exposures between the cleanings, maybe only 200, I'd still have been ok. But basically, my sensor was always dirty, and that's when I decided that this was unpractical.
My D800's sensor is entirely clean, and I don't have any of the other issues people talk about either, so apparently with the D800, I got lucky. I do believe though, that given the amount of sensor contamination, that the D600 does have an issue with this in general, not only some selected guys with bad luck or overly critical eyes
But I'm still keeping the D600, hoping that I can get it fixed in a few months when a real fix is available. It's a great camera.