I had a 76 Rameriz 1A that was 664 that somebody had file the frets very flat and was tough to play until I re-fretted it with some of the same fret wire used by Rameriz. It made a huge difference in barring. I used it that way for a few years and the neck gradually developed more of a bow, again making it hard to play. As I was approaching my Master's recital, I took it to Yuris Zeltins and he heat bent the neck for me. I was very lucky that he got to it right away because my recital was only months away and I couldn't be without it for long. When I got it back, it was a new guitar. It always sounded great, but now it was a real pleasure to play. Later on, I had an 82' Calidad Suprema from Jose Oribe that had a 666mm scale. It was a beautiful playing guitar! Now I have a 2005 Fritz Ober which is influenced by Hauser I and has the standard 650mm scale and 52mm nut. I love it, but sometimes I wish I could buy my 76' Rameriz back. On the other hand, I am intrigued by the various 640mm or even smaller scale guitars, especially now that I have been having some issues with my hands lately. I haven't had the opportunity to try one yet, but suspect the ease of play will depend more on the quality of the setup than the scale length.
2005 Spruce & CSA Rosewood by Fritz Ober, Yamaha SG100N with RMC pickups and polyphonic preamp with Roland ready 13 pin output