I have the same dilemma. I'm currently looking for a replacement of my daily drive, ml 420 cdi, and the first option was the 535xd, but now I'm thinking more about the cayenne diesel. The only thing I don't like about it is the lack of power and I don't know what to do about that. I can not wait for the cayenne diesel s. When choosing the 535 you have to take into account the depreciation which I believe will be major in comparison to the cayenne. Good luck with your choice and let us know about your decision.