This has nothing to do with hi-res/lo-res sensor. A dust is considerably bigger than the pixel size of a 10Mpix sensor. Therefore it will show up no matter what. The issue with D600 has been proven time and time again that it's this camera specific and not dust coming from outside since no lens change occurs and yet dust still accumulates. There is hope however that this is due to some scratches on the curtain and problem should go away over time, kinda like breaking an engine produces very small metallic dust which mandates changing the oil very early for a brand new car. Of course this is not an excuse for Nikon and they should fix/recall or whatever they have to do to retain loyal customers. Good Day.