@andrewd
Having a backup of all your music and Roon settings should be standard practice.
While no one has lost any music in the update process, we always recommend that you do back up just in case.
With regards Roon, the update will completely wipe your core, you will need to select a new core after update.
If you have playlists etc that you would like to preserve, then backing up to storage and/or external is required to be able to reinstate your Roon settings etc after update.
Do not backup Roon to Root, as this will also be wiped during the update.
Here is a wee instruction on Roon backups
Roon Back Thread