I would have to say that the best advantage over CD and other formats is the overall size of the MD media, and how durable the media is. Also, unlike CDs, MDs won't scratch, won't skip, and are infinitely erasable. Well, as any DJ knows, that is an outright lie. Pressed CDs scratch, bend, and break, just like vinyl. They are very prone to skipping from even the tiniest dust particle.
Some older CDs have problems with the paint on the artwork sticking to storage devices, etc.
CD-Rs are even more fragile. Even with the greatest of care, they scratch very easily, and just aren't compatible with all machines. I thought that MD could have been the best medium for Mobile DJs, but for those of us who insisted on keeping the instant start features and beat-blending abilities, MD was not an option. Inc. All rights reserved.