My $0.02.
Nav: I dont need it. I have a very nice Garmin Nuvi.
iPhone: I use the standard Iphone cable for my tunes.
I had it in my 328 and it was ok but the Nav was not as good as the Garmin Nuvi I use. My focus has always been just the performance of the car so all my funds have gone into mods. Yeah, it was nice to see all music choices on the screen with the ability to move around easily.
So, I assume you would be happy either way. As one previous post said, "those that have will recommend and those that dont will say its not necessary". To each their own.
