Interesting thread! Having recently acquired a Yamaki-made Jedson FW913, I've been doing some research on Yamaki. Their trajectory mirrors that of other Japanese manufacturers (Yamaha, Yairi) who came to prominence in the early '70s, by building high-quality Martin-esque acoustics, mainly from solid woods. By the mid-70s all but the top models were laminated and are now seen as less desirable.
Back to the question. In 1964, Martin produced only 6,298 guitars. In 1971 production peaked at 22,636 units. Somewhere between these two dates, the Japanese got the message, and a trickle of dubious-quality guitars became a flood of high-quality copies of classic USA designs. 'Badge engineering' abounded, and Yamaki examples turn up under the Fernandez, Canyon and Thumb (!) brands as well as Jedson (UK) and Daion (USA). They also made Washburns at one point.
So how good were they? An American luthier and guitarist recently sold a 1972 Yamaki F125 on Ebay for over $400. He commented that he played every Taylor guitar (around 30) in his local store, and 'none came close'. I hear the same comments from many sites where these early MIJ guitars are finally gettting the respect they deserve.
By 1981, musical tastes had changed, Martin's output was back at 1964 levels, and by the mid-80's the golden age of MIJ (made in Japan) acoustics was over.
Best wishes from Dubai!