I have a Xeenon Shuttle II. It is not as good as my Empeg, but it has some features that are kind of cool.
In the xeenon, if I am listening to the entire disk full of tunes, and I find one i like, I can change to the current playlist with 1 button. So If I am listening to \80s'\madonna\like a prayer.mp3, I can hit a button and the playlist changes to \80s'\madonna.
I realize you can have the same file in multiple playlists, but that would be a good feature.