I think it has more to do with the wonderful deep tone colors and resonance some of the chords produce... I remember seeing a Mudcat discussion about it but I can't recall where... but I know that on mine there is a sweet spot clustereed around several chords, and when I can get one in that range it sounds great. Especially now that I am hammering. But it's a bad range for me, for singing.
Now harp, yer jes' goin' have to do somethig with those expectations. *G* I bet I bust 'em all to flinders. I promise if we ever meet I will introduce you to that jook joint girl, and you can have a try with that song.