Good to know your observations. Sounds like if I was playing single notes it'd work fine. A chromatic harmonica should work well then. What about bending notes like on a diatonic harmonica? I'm assuming with chords things fall apart or get more difficult.
-- ScottyDizzle
Bending works perfectly.
Be aware that even if playing through this module with a mic and speakers I front doesn't really produce audio feedback, the pitch tracking will completely get lost. Personally I'm using a pickup mic inside a mute for my trumpet. For harmonica, you'll have to play with headphone for good results. Or with speaker set with a gentle volume.