Hi Vectis
I too had a yamaha FG140 when they came out and my then musical partner Colin Wilson had a 150. This was in the days of a great old time music shop in Exeter called Bill Greenalgh's where we had little HP books and went in on saturday mornings to pay the next installment!!
These two guitars were sensational. I foolishly sold mine on. Colin still has his. It plays and sounds as well as any top range guitar and has even weathered perfectly. The story I heard was that it was a deliberate ploy on the part of the manufacturers to make these guitars with solid tops and then, having created the market, they subtly downgraded the material quality with referring to it anywhere. The subsequent guitars were still nice but not a patch on the first generation.