Whistle Stop. I used the term "augmented third" rather than "fourth" because DADGAD seems to be Vestapol with that third interval "stretched"; but maybe I was on the wrong track. What you say about being pulled away from the major mode is probably a better way to look at it. I certainly like to play Carolan pieces with standard tuning (and maybe dropped D) because that doesn't have a definite mode attached to it.

Murray