For flying, I'd think battery life would be an issue. The Karma wins big on this one. Also, if you're traveling a lot managing your player might be something you're concerned about. As I understand it (and I could by WAY wrong as I've never owned an iPod), you can only manage your iPod from one machine and if you hook to a different one it'll wipe out your player since the existing tunes won't be on that machine.