I discovered the DADGAD tuning while I was in Canada in 1981 or so and then I was not convinced until i discovered that the IDEA of either open tunings or "modal" tunings may widen the possibilities of the guitar. You see, i am left handed and I never bothered to reverse the strings so...why not, hey?Mind you, I shall never give up standard tuning to play rag time for instance, but when it comes to play irish or "celtoid" (breton, berrichon, hibernian, caledonian, galician, old hungarian), I discovered a dandy G tuning: DGDGCD that may be transformed into a crazy C tuning by dropping the bass string even lower!! It needs a bitchy guitar like an old Larrivée and slightly heavier gaged strings.
I agree with Terry that then it also needs a collection of guitars on stage.
Salut