I had same choice - CPOed 2010 35d off dealer or 2011 X5 from carmax, don't remember options list though. That was very tempting to get 2011 for about same price but I choose CPOed one.

Well, I agree with Zeta, CPO is more like exclusions that actual coverage, I've been in for repair 3 times:
- EGR cooler (famous issue, you need to verify that it was replaced), was replaced as it was bad due to faulty party that was on recall, no CPO involved.
- rear camera flickering while car is hot - not covered under CPO.
- check engine lights on, diagnose - active urea tank needs to be replaced, this covered under CA extended emission warranty.

As you can see I have CPO car but i did not use it even once yet and it's about to go away in like 6 month or so based on age.