Intro skipping works pretty well once you set it up and give it time to scan. Functionally, it identifies common audio to determine likely intros, so it can get confused with shows that have different intro music between episodes of the same season.

Don’t have to change any folder structures unless you were storing optimized media alongside the original files in Plex. All the metadata for both Plex and Jellyfin lives in a SQLite database in your config dir.

You may wind up transcoding even if you think you really shouldn’t have to. Browsers are weird about supporting some encodings, and both Plex and Jellyfin will automatically transcode to satisfy the client.

Hardware transcoding is huge, don’t underestimate how impactful it can be. A single 4K CPU transcode could saturate my 72-core server, but one A380 can transcode 3-4 4K streams at the same time. This admittedly doesn’t matter much if you only have one user, but keep it in mind if you ever have to share. It’s so annoying to have a stream start hitching because 1-2 friends decided to start watching something at the same time as you…

I still don’t have a good replacement for Plexamp either. I think Jellyfin can play music too, but I haven’t tried it myself. I spent a lot of time getting the metadata right in Plex and just haven’t felt like trying to find a way to migrate yet.