There is no way to move to the next part of a song without a well timed hold (or a midi command). Let us queue this up with a single press of the external footswitch.
Having to hold and then release takes attention away from music during critical transitions.
Allow setup of the external footswitch (while playing and for bonus points when stopped/paused) so that a quick tap plays the fill until the end of the part and then starts the next part. Bonus points for allowing an option for switch at the end of the measure.
Start the transition fill upon press of an external footswitch, continues to play the transition until the end of the current part after releasing the footswitch.
I can understand why this may have been harder to add years ago when the BB first came out (since the external footswitch would behave differently that the main, multipurpose footswitch), but now it just seems broken. Saying that midi fixes this is a pretty annoying response…