I'm surprised at the comments against adaptive. Reading other threads nearly everyone thinks its the best think since sliced bread and I havent really read any negative comments!
With regards to any part going wrong, and if you are going to own the car longer than 3 years, then I'd say its wise to take out the extended warranty. There is more than can go wrong with a car than adaptive suspension and BMWs are not cheap to fix!!!
I wouldn't let wear and tear on components put me off ordering them