Quote>However, what is the write speed of the D600?<<<Quote
Good question. When you find out, please let us know.
However, I would assume it is over the 160 that a Nikon was rated at several years ago. Putting a 240MBs card in may be a good way to find out. The problem I see is that all these ratings are "up to" and I am willing to bet up to a million dollars (actually I can only afford $1) that they never reach near that speed in real life conditions.