I'm not seeing a dust issue with my D600. I have 1400 shutter activations and probably 50 lens changes.
We had a D800 post that demonstrated deterioration of the foam at the edge of the mirror box. Foam damage might be a source of dust.
One thing I do that may help is I have the camera set to activate dust removal when I turn it on or turn it off. I turn off the camera when I am finished shooting a scene. I might turn the camera off and back on a dozen or more times per day outside of lens changes. I also store my camera in a pack or on a shelf in a position where dust would not fall on the sensor.