The 550 had ARS which is the hydraulic anti-roll bar (front and rear). That's only part of adaptive drive. The other part is the variable shocks (which the 550 didn't have - thank god). I believe its these shocks that I have an issue with. That's why I liked the 550s ride and handling, but not so much with our X5.
Thing is...I did my homework and All X6s (from 08' onward) with adaptive drive use the same part number shock absorbers.
If you could order the ARS by itself I would.
We have active steering now, and that I think is great for an SUV particularly. I wish that was a stand alone option.
April 16 is around the corner. With any luck car should be in by 1st week in May
regards, DRP