I think it is just a matter of preference. My built-in keyboard metronome will do it all, with bell or without. I use it in all sorts of ways. It sounds on the same channels but is not recorded. I can hear it along with what I am playing. When I engage the recorder, only the notes are recorded. The metronome is the time base upon which the playback is based. For example if I record at 60 and later later wish to hear it at 75, I simply adjust the metronome and what Ive recorded at 60 plays back at 75. It's perfect for dubbing or assembling tracks recorded at different times in other places.Those old (antique) metronomes make wonderful decorative accents in a music room.