I set my BBF to the Rear Command Dial. Just feels more natural there than the AEL/AFL or EVF/OVF buttons for me.
Very annoying to have to switch from M to S, from burst mode to STILL FRAME, and Fine+RAW to Fine for teleconverter use.
Also not impressed with not being able to back button focus in any mode other than Manual Focus.
This being my first Fuji camera, I was pretty confused for a couple of hours trying to figure out how to configure the X100F.
Canon has a leg up with the BBF, Fuji!
That said, this is still a very nice camera and I plan to keep it.