I don't have Navi/iDrive, but I do have EDC.
Anyway, I don't think there's really THAT much you lose. A lot of the settings you can get to using the left steering wheel stalk. I think the iDrive allows you to set up a few customized settings that you can't get without it (i.e.: default the Power on, interior lights to stay on xxx seconds, etc).
2008 E92 M3 | 2007 Honda S2000 | 2001 Honda S2000 | 1997 Turbo Integra