Matt,
Country, bluegrass and blues maybe, but I can't for the life of me think of the gear-change helpful in any way in Irish singing - but I'm open to suggestions.
Your comment reminded me of a young woman singer who turned up here some years ago for a singing weekend. She had an extremely attractive voice in the lower register with a remarkable feel for her native narrative Scots songs, but insisted on singing in head voice. Similarly to the OP, she had a somewhat limited range and was constantly hitting her gear change, producing a yodeling effect, so much so that she began to constantly clear her throat. It totally spoiled what could have been a superb performance. Had I the confidence to approach her I would have suggested that she concentrated here work in expanding her lower range, which was obviously her natural one - I didn't, so I didn't.
Sorry Jack,
I have always got a great deal of pleasure from Jean Richie's singing and have also been extremely grateful for her pioneering work as a collector, but in context of this discussion I find her singing limited. Jean Redpath has always left me stone cold.
Jim Carroll