When you got to initially install & marry the COBB AP to your car, it'll tell you what ROM you have (IJE0S, I8A0S, IJE0S, IKC0S). They basically dictate which specific OTS Maps you download from COBB's website (
http://www.cobbtuning.com/AccessPORT...w/BMW-OTS-Maps).
I use IJE0S & have never had an issues with Boost Oscillations (even when using the
Beta Maps). Boost Oscillations can
easily be overcome by using an Older Version of the Same Map or getting COBB to email you a revision (just like get a custom E-Tune). You also have to remember the only time I've ever heard of problems, it wasn't on the approved/officially released maps.
I can promise you that the JB+ is a waste of money & will force you to make additional investments in the future if you continue to mod (JB+ basically adds a max of 5 psi, which only makes sense having on a stock car). I can promise out of all the majors, COBB & JB4 have the best customer service so don't worry about getting abandoned by the tuner.
IMO COBB is the least headache causing tune. Not only are their tunes bulletproof, but it's the easiest to Data Log & read Fault Codes with because of the AccessPORT. If you have any additional questions, you're welcome to PM me.