You guys should stick with oils that have the LL-01 certification from BMW. From what I have been reading on other BMW boards a majority of these boutique oils (Motul, Amsoil, Royal Purple etc..) do not have this certification, so your just wasting your money and not running the proper spec oil in your motor. LL-01 is used for NA motors running on NA spec gas, and LL-04 is used for Euro motor running on Euro spec gas. Here is a spec guide straight from BMW NA on what oils you should use.
Personally, I will only use the BMW HP 5W-30 Synthetic Oil or the Castrol Syntec European Formula 0W-30 for my 335i (See Mike @ Maranello for specials on the BMW oil or check the Crappy Tire flyers for the occasional Castrol sale)