Boy am I going to get spanked here or what.
I can honestly say that I never use the nav device and I can't stand it! If I could have deleted it and gotten the traditional 540i dash I would have. Now I have to admit that unlike others that have responded to this post, I rarely drive into different areas or states that I'm not familiar with. Maybe if I got out more (!), I'd like it.
Guess I'm the only M5 owner that can't stand it!
DWP