Recently I've been hearing about portable mp3 players that are capable of recording directly to their internal drives using either internal or external microphones (they have optical inputs/outputs as well). I know MiniDisc has been the predominant tool in recording live concert material, but these new devices seem really nice. Has anyone had any experiences with these?

I am considering getting an iRiver HP120 that has a Line-In jack for an external microphone, but hardly anyone has commented on their recording quality compared to MiniDisc. Mainly I'd like to use this to record live shows. Any opinions are appreciated!