Apparently there were three versions of the D-25M early on: 1. Flat braced back with a mahogany top, 2. Bowed, unbraced back with a mahogany top, 3. Bowed unbraced back with a spruce top. I have one of the 3rd variety, produced in 1976. I bought it new with hardshell case in '76 for $300.00, about 1/2 the price of a Martin. I played the Martins, the Gibsons and the Guilds in the same store and quite frankly, the Guild's wood and finish looked richer, the sound was deeper, and was a bit heavier than the others. Its been to a thousand campfires, gigs, jam sessions, etc. and it's still straight and true and has piano-like sustain. A new set of D'Addario phosphor bronze mediums makes her sing like an angel. It has a few battle scars but it was certainly "made to be played". At any rate, I'd like to play all three varieties side-by-side to compare, but my guess is that each has a great sound. Interesting to note that two of the three "M's" had spruce tops...