See here (at UPDATING FILES & COMPATIBILITY WITH PREVIOUS VERSIONS):

https://www.rpmseattle.com/of_note/finale-version-26-review/ 

Since that article was written, the trial period for 26 has been extended to 60 days.

https://www.finalemusic.com/free-trial/

Best way to figure out if the upgrade is right for you is to check it out for yourself.