It's deeper than that. I think this informative post
from Santo will answer the question of what's been changed. I would recommend reading the PDF first and then following up with chapters 4 & 5 from the media event.
My biggest concern, possibly baseless, is the change in wrist pin offset. If this is a north america only engine that was just introduced last year, then its track record is very short.
, in particular, raised an eyebrow. Most likely a "one-off" but does this reflect the US mods? At this point there probably wasn't a large population of X5d's in country and therefore the failure rate, percentage wise, is higher.
Craig B and jaaX3 have also experienced the joys of warranty repair within the first year of ownership.
Clearly, patience and, as stated above, a nice warranty are you and your BMW's best friend.