With the PA 800, I set up my registrations for each song, insert them into a custom list in the order I want to play them, and punch 'next' to get from one song to another while noodling on some variation of a minor ii and dom. 7th. Pretty much the same with the Genesys XP - from a 'memories' list, punch a song number 1 thru 8. With both instruments, I most times add a fill with the foot pedal during the transition. I also use this method when changing tempos for the same tune - eg., some of the Prima tunes go from 6/8 to a fast jive/boogie/shuffle or whatever.
Ciao,
Jerry