Some versions of Shady Grove are minor and some major. We've sung both vocal parts at the same time (with two singers of course) in my band. It kinda works.

I alos like switching from major to minor after each verse/chorus.

I play the minor version in Em and also Dm like Doc Watson does. I play the major version faster, more like a breakdown.

IMHO the minor version does not closely resemble "Pretty Little Pink" songs but the major version does.

Richie