After a couple of days of testing I have finally successfully moved my music media from one location to another and preserved all the metadata including the guid="plex://xxx for artist, album & track which I was worried about.
Using the procedure I linked above from plex did not work for me. It works for movies & tv media but not music. Anyhow, I ended up with duplicates of everything, had problems saving changes to the library settings once I added the new path to the new location of my media and it took WAY longer.
I opted for a plex dance approach for my entire music library (minus 1 album as you need to keep 1 there so plex will process a scan). Then after the empty trash step I changed the music library to point to the new target music location. After it completed the final scan and matching everything linked up correctly. You can check that via the dashboard history as the history for your tracks should link to the actual media. If it failed then these will be greyed out.
Leaving this here in case its of help to anyone in the future.
