So I've also owned multiple M3's. I purchased a 2002 and sold it 6 months later to buy a 2003 when the SMG gearbox became available. It put 50K hard miles on that car and could not break it. As for the Y vs. X3 question, the vehicles are so different that it should be an easy choice for you if you drove each one. Do you want to live in the future or hold onto the past?