I found audiobooks to be kind of awkward on jellyfin. I'm now running Audiobookshelf for all my audiobooks, radio shows and podcasts. Together with the Lissen app on Android, it works very nicely!

I've heard rumors that they do play well together, but that's people running it in docker with a "read-only" flag set for the content folder, with metadata saved in the config folder

I've used the Jellyfin app to listen to audio books, but for my purposes, it's easier to run the separate client/server Audiobookshelf.

My Jellyfin and Plex containers were able to use the same locations for media.

I've had Jellyfin and Plex running using the same media directory for a couple years now. I think I had to make a couple small changes for things like seasons of a TV show to show up correctly, but nothing incredibly difficult. Definitely worth setting up and playing with periodically so when you do finally get sick of Plex, you're ready to just switch.

Only thing I use Plex for exclusively now is when I'm flying, Plex has the Netflix style download option and Jellyfin just downloads the video file. I like Plex's way better just from personal preference.

I haven't used Plex myself but Jellyfin doesn't create any kind of meta files in the library folders. If that is true for Plex as well then I don't see why it would be a problem to point them at the same shared library.

Of you use docker plex and jellyfin arent gonna be messing with your media unless you delete/modify them within the respective clients (but then again thats what *arr is for)

I didn't enjoy using Jellyfin for audiobooks, on my android I use the Jellyfin client to download the book I wanna listen to and then I use AudioAnchor for listening to it.