Traditional Irish Music
In the ensemble group I'm in there's a girl who plays viola. She attended a fiddle workshop a while ago and that helped her a lot. She's quite good at jumping up to higher positions for certain bits in the tunes, but we don't play quite at session speed, most of the time, so I don't know if that'd really work. I think the thing to do is to take it one tune at a time. See what works. Some parts work well enough an octave down. I hope some more knowledgable folk will chime in.