I owned a PA 800 before jumping to the 3X when it came out. But I never really tried to import any songbook data across so no issues would have occurred for me.

Back then I never used the songbook. I Found it extremely tedious to setup and access (The New Set List function completely helped modernise and add the much needed convenience) so instead I was just using custom performances and I moved them across very easily to the 3X without issues.