John, What a conincidence I use the Pa4x and S970.

Songbook in the Korg is tops but when it comes to the S970 I use the MFD system and registrations. I usually use registrations to change voices, but lately I’ve been using registrations to choose, style, key, volumes etc. As far as the MFD system, I use keywords on every tune. The simplest example Is Christmas, i use the keyword Xmas, then when I want to pull up all Christmas tunes I do a keyword search using the “search 1 or search 2” once the search is completed I have all the tunes for Christmas listed so I have a playlist for Christmas.
With Korg Songbook I do something similar except I use “genre” and assign a number again with the Christmas example I use the number 9, for Christmas tunes and use the filter and again that yeilds me a list of Christmas tunes.
ON another note Yamaha’s new Genos allows the user to save registrations in a Playlist. Seems they took a lesson from Korg’s Songbook.