I have a pretty significant library of both ripped and purchased music so I just signed up for Match to listen on my work computer. The problem is that almost everything has custom tags for genre and star ratings; I use star ratings to generate the playlists I sync over to my iPhone. I don't want iTunes to decide to Match my ripped songs from some anthology, for example, so how do I best approach using Match. If I keep my library on my computer will Match change the tags on that? If I upgrade to a Mac with a smaller drive and rely on Match to hold the bulk of my library, how do I make sure all my custom tagging is untouched?