I waited for BMWUSA for nearly two years to decide to bring that engine model to the US, but finally gave up and bought a 535i. Would much have preferred the diesel. It's been nearly two years now with mine, and although there are hints they may bring more diesel engined vehicles into the US, it hasn't proven true (yet?!). Love my comfort seats, but not sure I'd have opted for the larger wheels. I think you'll like it long-term. My best tanks were all highway on a long trip where I got a bit over 37mpg - Imperial, or 30mpg US. I'm sure yours would have gotten better under those circumstances - essentially non-stop at a constant speed with no secondary roads at all.
When I was in Harrogate last fall visiting my sister, I picked up a RightConnections towing electric harness package and installed it myself. It doesn't need any reprogramming to work with the camera, stability control, PDC control at all. I use it primarily with a cycle carrier and I also picked up a light board to tell the system there's something behind. I think the 13-pin DIN connector is much nicer than the standard ones used in the States. I bought a couple of extra plugs to make adapters, should I need to pull something rather than the lightboard and cycle carrier.
Good luck...I'm sure you'll love it in the long term as well.