One thing I do on my Genesys pro is assign the fill >, fill <, fill to self, vocal harmony on/off and the start-stop to foot pedals.

This helps in two ways: it makes me avoid pressing the fill buttons with my hands, thus freeing up my hands for other thing such as playing the keys and muting and on muting style tracks.

Also, I can sound more like a real band since I could have fills anywhere in the song because when I put in a fill is not dependant on whether or not I have a free hand.