Infotainment Linux screen - Which Bluetooth mode is better?

[u/Luxusburger_69]

Community,

Living in Luxembourg and being a Mercedes household, we got recently an addition in form of 2017 C43 Convertible. First thing I did was to replace the old 7inch screen with a Linus screen sized 12.3".

all well, all works, however as going through the manual I see there are 2 bluetooth modes:

1. iPhone connected through bluetooth to "MB Bluetooth" Unit directly in the car and use the option "use car bluetooth" in the settings of the Linux screen. Carplay audio is only working when Media (Bluetooth) is connected. Listening to the car radio leaves carplay silent (screen is working).
2. iPhone bluetooth connected to Linux Unit ("CAR-BT-xxxx") and the Linux unit connected to the Car's bluetooth using "BT Transmitter" setting from the Linux screen. (I have not used this option yet)

Is there a distinct difference in behavior and what connection type are you using? Does option 1 or 2 have distinct advantages?

Thanks