+1 for the two posters above I don't think it will last as long. You may also go to leave to go somewhere to find out you have a dead battery. The 335i has a lot of components that run after the car is shut off to keep oil in turbos cool and them if you have more options like navi and many other goodies your car needs a larger battery BMW actually requires a minimum amount of miles driven per day or to buy a trickle charger to keep life in the battery. BMW also has made battery's larger because of those issues.
I'd also say that 40 plus pounds keeps you closer to that 50/50 weight ratio I'm sure you need the xdrive but Id reduce weight by going to 335i