Unfortunately, I returned the handset before exploring the Microsoft sync account setting (although I do not recall coming across it in the menu system ). But isn't that for e-mail/calendar synchronization? If so, I do not think it has anything to do with media playback through the SYNC system (Ford's audio integration system sourced from Microsoft)

On the original problem and the need to place the unit in Mass Storage mode to allow SYNC to index the music on the phone, I believe that this is a small flaw in Android's design. I did some research and found that the difference between Mass Storage and MTP is the scope of the lock on the file system. Mass Storage locks the entire volume (SD card in this case) which prevents Android applications that need to access it from doing so. MTP on the other hand locks individual files while they are being accessed. So unless the Android application is trying to modify the file being accessed by the SYNC system, it will not be prevented from accessing the SD card. Perhaps a future update will correct this shortcoming.
My 'not so smart' Sony Ericsson J105a phone allows several options for USB connectivity and MTP is one of them. This allows the car audio system (SYNC) to index/playback music stored in the phone's SD card without affecting other applications that use the SD card (e.g. Camera), as long as they do not access the same file at the same time.

Another shortcoming is Android's omission of Text Message support via Bluetooth. Again, it turns out that the phone should implement a particular Bluetooth 'profile' to allow an accessory (Ford's SYNC system) to read SMS text messages off the phone and play them audibly through the car's speaker system. Here again, my Sony Ericsson phone beats Android and iOS devices, neither of which supports this Bluetooth profile.

Does anybody know if Gingerbread supports these features?