I saw one once on TV played in a Mariachi band. My thought was, "Why bother?"

For me the appeal of a fiddle is in the "fretless-ness"--I can get a LOT more notes and slides than a fretted instrument. I can "bend" notes easier than a fretted player, and I can make weird sounds like Alley Cats, or Ghost Riders..........

If you don't like mandolins, check out mandolas and ocatave mandolins..........to me, at least, a "fretted fiddle" is an oxymoron.