I owned a 2008 MDX (after owning an E53 X5) and switched back to the 2008 E70 X5 after owning the MDX for 6 months.

You are completely correct about the navigation, iPod, parking sensors, and backup camera. Thankfully my spiffy 2010 X5 solved all of that and BMW throws in top view to boot.

But -- I thought the MDX sound system was disappointing, nothing better than the MDX. Honda is pretty famous for dull stereos. And for the driving aspect, that was my primary reason for leaving the MDX. The MDX lacked feel and felt too much like a truck for me. The engine had less power (even though it's rated higher) and a slower 0 - 60 (by a little bit). While the MDX was a little smoother on bumpy roads, it also was softer in the twists. Finally the MDX interior felt cheaper to me, lower leather quality and some harder plastics.

But I don't fault you at all for switching. Get what you are happy with and enjoy it. BMW isn't Acura or Lexus, the entire experience is different (more raw in my mind).

Happy MDXing.