This is a great question. For reference, I just came out of a Lexus GS450 hybrid with the Mark Levinson. I think the BMW Premium is comparable but, and this is a big but, the Lexus is a significantly quieter car with far less road/tire noise so the end result is that no car can come close to the Lexus sound when the car is moving. It is just amazing. The BMW is not far behind but it does compete with greater background noise.
Of course, you cannot compare the driving dynamics between the cars. Whatever 'sacrifices' you make with the BMW sound system are 10 times over worth it in the fun factor.
2009 e90 M3 DCT - Jerez Black/Fox Red Extended Novillo Leather - Every Option Available! Former 2003 M5 and 2001 X5 owner