While I understand the yen for rating, I question its need. Rating seems beside the point to me somehow. In folk music--or any kind of music, really--I respond to the entire presentation. There are some technically very advanced players of all instruments that play without passion...and since feeling rather than technique is more important to me, their performace as a whole tends to leave me cold. Sometimes very simple instrumentals, let alone simple accompaniment, can be devastatingly moving.    If I were looking for a teacher, I'd look first for smiliar tastes in music, then a like sensibility, and only then figure out if the teacher was "advanced" enough to teach me what I wanted to know.