I recently read of an interesting classical travel guitar with a detachable neck developed by the Argentine luthier Nicolas Rodriguez Guerra. He calls it his model DÉMONTABLE. The young German guitarist Julia Lange has played it in concert while on tour in France so it must be of good quality.
A high-end classical guitar shop in Lyon/France sells this guitar. I have not tried it but the shop has posted videos of it on YouTube which are easy to find by searching the luthier's name. What do other luthiers here think of this? It seems to work very well.