I'm thinking of buying my wife a used X5. I would love any and all advice from people who have experienced these vehicles (X5s in general) or just want to add thier thoughts. I particularly thought about the "is" versions because they are essentially "M" versions of the X5 and as such should have a heartier, albeit pricier, drivetrain. This vehicle would replace her current E46 325i. Thank you in advance.

-Orlando