I just did a migration of my Plex Server stuff from the Limetech repo to the LinuxServer.io repo.
I got tired of waiting for a a version update so I just switched to the LinuxServer.io repo for Plex from the Limetech one since LinuxServer.io keeps theirs up to date.
Here are the steps I took:
[*]Make note of your container mapped custom media path settings if you have them specifically set for PMS (for instance mine map /Media to /mnt/user/Media)
[*]Shutdown the Limetech PMS container, but don't delete it yet
[*]Backup your appdata config for PlexMedia Server (mine was in /mnt/cache/appdata/PlexMediaServer) to another folder for safety
[*]Add the LinuxServer.io Plex container. It can coexist with the other one temporarily as long as the other one isn't running since they're named differently
[*]Add the mapped media path you had in the Limetech container settings if you had it set there. It's not there by default in LinuxServer.io (although you could use the /user mapping that it does come with, I prefer a direct reference for isolation)
[*]The LinuxServer.io container will automatically startup after you're done setting it up and saving/apply. Access the server via the webUI and log in.
[*]Once the new Plex container is up and running after initial wizards, shut that container down again.
[*]With both containers shutdown, copy all the content from /mnt/cache/appdata/PlexMediaServer/Library/Application Support/Plex Media Server to /mnt/cache/appdata/plex/Library/Application Support/Plex Media Server (or whatever old and new Plex paths you have for the appdata stuff)
[*]Once you're done copying all the appdata stuff, startup your new Plex container again.
[*]Access the new Plex server via WebUI or from the Plex.tv site. Verify all your content, settings, channels, and custom Agents survived the transition, and that you're on the latest 1.0.0.2261 version in the Settings/Server page
[*]When you're satisfied everything survived the transition, you can delete the old Plex Media Server container.
[*]Update any other container paths that refer to your Plex Media Server install (i.e. the logs path for plexpy) since it will be under a new location in appdata
Hope this helps.