Hmmm, I dont know how to really help in your situation as far as concerns go for the German electronics.
You sound like you really love the F30 design, so Ill put it this way. Build an F335i M sport with a 6 speed manual, dont get all the options or bells or whistles. Do the m adaptive suspension and steering for track purposes. Do a basic build that way youre not too worried about all the technology go wrong. Im not sure about your saddle brown interior if its available with M sport, I know those packages can get stupid with whats available with what.
I think sticking to the m sport the car will definetely age better, because you plan on keeping it for a long time.
Good luck with your decision.
Custom Modified OEM Muffler,