Just purchased a Alpine CDE-HD138BT unit for my car. This unit supports both phone and audio bluetooth. The phone works fine except for some of the advanced features don't work (not concerned about this). The Audio profile also works for media and for Pandora.
The problem is when I want to use the special "Pandora BT" mode on the radio that allows the radio to directly manage the Pandora application. (Stations, Likes, and display the artist/title) If I delete the bluetooth connections in both the phone and the radio and pair the devices back the Pandora mode will work until I leave the car. The next time I go back the Pandora app will stop working. (Pandora will still stream through the standard BT audio mode).
As a test I also paired my old original Droid (using Wi-FI for Pandora) and it works fine and reconnects fine.