The reason slot loaders are not popular is because they are infamous for scratching disks. They are in cars because they are convienant, but I only use backups of my CDs in my truck because I have CDs getting scratched and I am gentle (borderline OCD!) I also have a friend that use to work for a company that repairs CD players and he was the one to enlighten me. Slot loaders also have a serious problem with those "stickers" some people put on CDs (instead of using a sharpie). The sticker will pell off inside the CD player as it's inserted and cause all kinds of problems, you can't simply pull the CD out.