I think a number of the old blues players used open tunings, didn't they? I remember reading where Joni Mitchell seriously got herself on the wrong side of (?) Furry Lewis by saying something about playing in the same tunings he used (it has a name, which I can't remember at the moment - Sebastapol? Vestapol?) and he got the idea she was patronising him, and became hostile and defensive about it. She says she was just passing a neutral comment and he put some kind of negative interpretation on it. But if open tuning is "cheating" - which I don't believe it is - then Nic is is some pretty stellar company.