A few months back I restrung a ukelele and tuned it in a fiddle/mandolin tuning, and have been playing around with it. It's great fun to play. (Someone here suggested I call it a mandolele.)

I just checked and found it is exactly the same scale length as a fiddle - which explains why, when I picked up the fiddle the other day I found my fingers seemed to be in pretty well the right place. I think the main interest with the Fiddle Fretter, when it comes, will be to find whether I prefer the sound, in line with that quote I gave earlier from the Oxford Companion to Music about frets - "they exist on viols and lutes in order to give the strings, when 'stopped', the resonance of open strings, i.e.to obviate the 'softening effect of the finger tips."

The big stumbling block for fiddling surely isn't really so much the intonation, even without frets, it's use of the bow.