The round pin flat pin issue has nothing whatsoever to do with MOST (Media Oriented Systems Transport), which is the optical system used in the newer BMW's, E60, E90 etc.

BMW make adapters so you can install flat pin radios in cars with round pin harness :

61.12.6.913.957 Round Pin to Flat Pin Main Radio Harness Adapter
61.12.6.913.955 New Gen Radio Antenna Adapter
61.12.6.924.785 10-Pin to 12-Pin Radio Audio Input Adapter
61.12.0.140.716 CD Changer Audio Input Cable
82.11.0.149.390 Aux Input Adapter Kit for New Gen Radio