Irish traditional (fiddle) is stuck in first position, which is fine for tunes in D, G, A. Em etc, which is all that the music ever requires (the music also accommodates pipes and whistles, which are even more restricted). Learning classical opens up massively more scope than needed for Irish traditional, but if more fiddlers learnt it, they wouldn't have to put capos on their mandolins (sacrilige!) to match someone singing in a remote key.
I'd say if someone is interested in traditional/bluegrass/oldtime, learn just that, and move on to classical if the urge is there. One of the most important, or at any rate helpful, factors in getting a youngster started, is finding one or two like-minded people among their peers.
Numb-brain JoeClone deleted the wrong duplicate message, which said it was posted by "GUEST,Fionn (still lurking in County Down)." --JoeClone, with apology.
JoeClone, I am extremely worried about this. We were all cloned from the same source. Does that mean that I am a numb-brain too? Or worse still... ;-)