I tried one of Dwain's dulcimers at a festival a while back. It had the extra 1 1/2 fret (don't know if it was a flexi). Beautiful instrument, but on short acquaintance that extra fret was throwing me off completely. I needed more than 20 minutes to get used to it. On the other hand, the flexi idea makes a lot of sense, and I've been tempted. The ones I saw on his instruments looked nice and the fretboard was smooth when they were out (a consideration if you like to slide between notes with your fingers). A number of folks on the Sweet Music Digest, have them and like them. Proper installation would be critical.