Thanks for the posts, I am wondering if there is a simpler solution. I don't want to buy additional backup software. I don't need to keep everything continuously synchronized.
Would it work to just save a library backup on the desktop PC, delete the music folder on the portable SSD, copy the entire music file from the desktop and paste to the portable SSD, then restore the library backup on the laptop?
I would just do this as needed, probably about once a month.
Yes it would work, but copying all your media files once a month is overkill. IMO it is well worth the investment in a folder compare utility such as BeyondCompare, or maybe try a free utility such as WinMerge.
Then use the comparison software to copy only the new or changed albums to client's own media drive. MC automatically imports the new files into its library, including the artwork. The whole thing flows smoothly when both server and client use exactly the same folder structure for audio media. I've been doing this "manually" for years for two different clients, without "automatic" continuous syncing. There are possible gotchas with dynamic fields like "last played date" if not saved to tags, but it sounds like you may not care about that.
I find there is no need to go the full library save / cross restore route until there are significant changes in my server's views, playlists, custom fields, etc. which I want to incorporate on the clients.