Is it possible to physically remove the wifi/bluetooth card so that I can use the BT USB dongle instead? Would this avoid the confusion of which BT to use?
The BT in my H77N-WIFI works fine. You do need to remember to have the external antenna connected (the one closest to the HDMI port on the back). That's the only "gotcha" I can think of.
You do need to remember to have the external antenna connected