Thanks. I would love to get more information, especially on those paper label models with the gold Martin logo on the paper. I'm starting to think that there is a strong possibility they were not exported, or that if they were it was in small quantities. Would love to know more.
The Sigmas we most commonly see in the US are definitely budget models, designed to not compete with Martins and offer a budget alternative (laminated bodies, etc.).
However, there were some that were great guitars. Some had solid bodies, although it can be really tricky to tell because Japanese luthiers were so good at matching grains, the inside and outside grain can look very similar even on a laminate guitar.