Old Time fiddler's and Mozart have been known to use scordatura. I'm currently away from my computer and my music, but I believe the original viola part for the Mozart violin/viola concerto was in scordatura. Not complicated, just up a half tone, and Mozart wrote the part the way it was to be fingered (i.e., play it like it looks, and it'll sound right). I hope that makes sense.
When Ruth Porter Crawford was doing transcriptions for "America Sings", and she transcribed William Stepp's "Bonaparte's Retreat", she transcribed it twice: once as it sounds, and once as fingered (in Stepp's tuning) as if the fiddle was tuned "normally". Make sense? (Aaron Copland later lifted Stepp's version note for note, without, as far as I know, giving Stepp any credit.)
Hope this helps,
Ralph