I switched on iTunes Match so I could free up the 40GB of disc space my music uses. I have another MBP that has the full library (no iTunes Match) and backups galore, and I don't listen to music much on my MBPR anyway. So after aeons of uploading it's all done, and I've selected all the tracks in iTunes and deleted them from my local drive (kept on iTM). I've checked the folder and it's gone from 40GB to 3GB, and I've emptied the Trash can, but I still don't have much (any?) additional space on my hard drive. Any suggestions?
Ok, so I now have 46GB free space. I didn't do anything, it just suddenly appeared 24 hours after I deleted the local files. Ah well, jolly good.