hi Mike. GOOD question.

It's not just hard, but it's IMPOSSIBLE to achieve via the front panel, while concurrently playing as well.

As a 2 handed player who plays fully voiced chords with the left hand while my right hand plays melody & fills, it's already difficult enough for the left hand to leave the keyboard momentarily (without losing the left voice instrument) to hit a fill button, but it's VIRTUALLY IMPOSSIBLE to be able to press and then HOLD a fill button continously thru several measures and be able to trigger the chord changes as well. The 'continous looping' fill to self function is extremely 'useful technique' to build song energy (and subsequent audience enthusiasm) thru several transitionary measures which frequently involve chord changes as well. This is IMPOSSIBLE to achieve without a foot pedal and the 'fill to self' repeating feature. - Scott