I don't have any need for the nav, but with ZCP, you don't get some of the special features w/o iDrive, such as the Sport + settings. Kinda pissed me off when I found this out after getting my brand new 2011 e90
Mine is pretty stripped, btw. I love the manual seats, but I miss the great sound of the premium sound system. That is my only regret (and not having the special Sport+ settings
)