so_la_la, I was going to reply to another thread of yours and I just saw this.
I have a Lumia 820 (running Denim etc), and I'm having the same issue as you in regards to syncing. I'm trying to sync three (fairly large) playlists to my phone (over 25gb). Last time I finally managed to get it working, this process took over five hours to complete.
The problem being that for some insane reason my Windows Phone 8 device is fantastically slow talking to my Windows 8 laptop, and whenever I sync my music ALL of the tracks are re-copied over to the device.
Like you, I'm using .PLA format for the playlists, and copying over to an SD card (which I checked had the fastest read/write speeds I could find).
I saw in another thread that you were possibly going to move your music collection to OneDrive... But I wonder if you ever had any success with MusicBee?
(Also, I've never been able to get playcounts to natively sync, I am sure I remember reading somewhere that it isn't actually supported by Windows Phone?)
