Still struggling to see the advantage of carrying around a bunch of disks as opposed to just taking a large capacity MP3 player. The iPod, for example, can hold up to 30GB. I have a little less than 10GB of MP3s on my computer (all legal, thank you) which would play straight for something like 5 days. So extrapolating this, I could hold about 15 days worth of music on a 30GB iPod (most of my library is encoded at 192KBps, YMMV). Obviously the battery wouldn't last that long, but it is rated for 8 hours or so.
And how do you not need anti-shock for MD? Maybe I'm just not familiar with the technology -- but it's still reading the disk by spinning like any other optical disk, right? So if hit hard enough, that tracking mechanism would skip.