Personally, i tried making a radiused fretboard once years ago. As far as I understand it, the main benefit of a radiused fretboard is that its easier to apply pressure for things like barre chords. I dont think this matters as much on a dulcimer as on a guitar, since it takes a lot less force to fret a dulcimer in the first place.
radius fret-board.
My guess is that if you play in modern finger picking style it would be helpful, but I've never played a mountain dulcimer with a radiused fret board. I see that some banjos which have traditionally had flat fret boards are now being made with radiused fret boards. There are some dulcimer makers who are doing fret boards with a radius, but I can't remember who they are. As to pros and cons, I have no idea.
Ken
"The dulcimer sings a sweet song."
Someone did one years ago, one of the luthier fellows. If you are a picker it would make an ideal set up with a four string. I can't imagine any reason it would be detrimental, but the sages haven't spoke!lol
As in all things here, try it and let us know how it turns out...I would but I can assure you it "won't" work with staples! 
Hello everybody, question about radius fret-board.
Pros.?
cons.?
