Kind of in the same boat minus the already waiting part. I just put my deposit down on a 2013 335 and since I'm stationed here in Italy, I can get the car in January no problem but now from doing a little research and learning about the Nav I'm debating holding out. This means I'd have to wait tell July...and that sucks! Like you said life is to short to wait for inevitable changes. I wasn't even going to get the Nav to begin with so this shouldn't be that big of an issue to me but like most of us...we want the best newest thing and since we are paying a hefty premium for it, we want it.
Right now I'm just tying to go over in my head the major pluses with the new system. A few more gigs HD, some cooler graphics..etc. yada yada, there is always going to be something new coming out, I chose this car because it's a blast to drive and I wanted to step my game up in the luxury/comfort area not because I needed a computer to tell me where to go.