You're right — a few of them are hold, not power. Even the OG shuffle, which definitely looks like it's a power switch, appears not to be — when I switch it "off" during playback, there's a suspicious delay before the music stops.
It’s been a while since I used my iPod Video/Classic, but I think I remember being able to turn them off by holding the Play button on the dial for three to five seconds. Maybe that was just the hard reset; I don’t remember.
