i was in the ame boat as you. took me a while to make up my mine. I've had my m3 for a few days now. I don't miss the 335 at all. This thing is a totally different beast. It just " feels" better. It's hard to explain. Nothing wrong with the 335, but this has been debated a 1000 times...
Mineral White + HRE + Brembo + Eisenmann + Challenge = Perfection