I have a 2002 MDX and a 2005 Cayenne S.
Although both are great cars the 10K difference gets you:
1) Vastly superior performance - acceleration, braking, handling (one is better than 95% of cars and the other is worse than 95% of cars) full time four wheel drive2) Vastly improved interior - seats, sound, driving position
3) Fun to drive - the cayenne puts a smile on my face every time I drive it, the Acura is far more utilitarian4) Safety - more air bags, traction control, roll over stability, brakes, etc.
However the Acura is better at:
1) Interior space, even though the cayenne is larger outside (slightly) the Acura is much larger inside. Even with the third row set up, there is more "trunk" space and more storage compartments (I especially like the storage compartment in the floor) Needless to say, when we go to home depot or Costco, or have seven people, we take the Acura2) Gas mileage - 18-19 vs. 12-13
3) ac - cools fasterSo in sum if you value performance over space take the cayenne. I love the cayenne so much that I am planning on trading in next year when the cayenne is redesigned. I am hoping there is a strech version similar to the Q7.