Thank you for all the info.
I have an E91 2006 and want the Bluetooth, USB and the new gong. I didn't want to install the complex MULF or TCU modules as they are too complicated and expensives to install. Also, my old CD73 radio display has lost some pixels so it's time for a radio swap!
I have ordered a new HU on EBAY, USB cable, socket and Y cable. The radio is coming with a compatible micro so I will see if I need a genuine BMW or not.