As discussed here in forums, some people were stuck in understanding how the Lbrary Sync feature works. I was one of them.
I got my Music stored in default MyMusic folder on my Laptop and a copy of this folder is stored on my Windows Home server in server's Music folder. At the moment I am syncing these folders by means of SyncToy, which lets me keep the local laptop library synced with server's music.
Whenever I tried to use Library Sync feature, it started to copy my music files from the server onto my Laptop. But in fact I have those files on it already, that resulted in creating duplicates. Also the existing Library Sync features copies files not considering the folders they are in. Yes, you can set Artist-Album topology but in my case some of the files stay in Artist/Album folder and sometimes they plainly lay in Artist folder as well as some folders hold music for many artsits.
I think it will be a good idea to implement folder syncronisation but not just the library sync the way it works at the moment.