The have really bad resale value here in Germany.
I tried the MKVI style palmkeys on a Elimona Sopranino and they seemed usable.
What about Martin? I've never heard about these?
I don't think a buescher or conn or similar vintage similar is good for me know. I don't want to spend all that practice time just to get used to an instrument ( just recieved an '19 Conn bass from a total rebuilt - lot of practice still to do^^)