Being OCD, I've longed to have my entire collection in 256k .aac format. I've bought from iTunes, eMusic, Amazon mp3, ripped from CD's, and have used other acquisition methods since I've began digitizing my music several years ago, my iTunes library was full of various bit rates and file types, acquiring over 20,000 tracks. Despite all the various sources that my music comes from however, I'm always proud of my pristine tagging of my library. Every song, artist, album, artwork and year is associated with my tracks. And now thanks to iTunes Match, all my tracks are good quality copies of 256kbps .aac/.m4a files. iTunes Match was able to match 18,000 of my tracks, in which I've used the delete and re-download method to get iTunes DRM-free high quality file (yep, I downloaded 18,000 songs directly from iTunes!). The other 2,000 tracks I was able to re-rip to 256kbps .aac from CD's and FLAC and have iTunes Match upload those. The rest of the 650 tracks I've apparently purchased from the iTunes store are now DRM free (and some I thought I had lost/accidentally deleted). Of course the size of my library, in terms of storage space, as swelled thanks from going up to 256k up from 128k (my early CD rips, unfortunately were this size and in .mp3), but it's a non-issue since I use a 4TB external drive. Life is grand. My library is finally exactly the way I want it all the way down to the file level. If you're own the fence about purchasing it, I highly recommend it.