Be careful with non hubcentric spacers. I have 5mm on the front of my 535d and I was getting a vibration due to the wheels not sitting on the hub properly, due to the internal chamfer on the wheel bores it allowed the wheels to move around on the hub no matter how tight the bolts were. The solution for me was to use Hub extenders as well as the spacers.
If you can I think I would prefer to go for a hubcentric design which may mean going up to 12mm. Also make sure the bolts go in at least 5 threads.