I don't have an arched-back mahogany top version, but I do have a flat back all mahogany (1970) and a arched-back spruce toped version (1974). They are both awesome, but different. Mainly I am the strummer in my band. For that use, I love the 1970 as it is lightweight and extremely resonant and lively. But that gives the K&K Pure mini I had installed a sort of sonic overload. The 1974 is about 12 oz heavier, and similarly loud, but individual notes are purer and the sound is more focused. I don't even need a preamp or any eq for the K&K in this one. For single note runs, the difference is not as great as there are fewer sonic waves bouncing around at the same time when you play that way.
I have also recently picked up a '73 D-35. It's weight is in between and has a flat back with spruce top. It seems to be right in between the D-25s in tone too. It is in the shop right now getting a K&K installed, so I'll know how it handles amplification soon. But I can say this, while the D-25 was the affordable Guild in the 1970s, they certainly don't lack in tone.
And finally, all that added 1970s structure is a double edged sword. I really like the light weight 1970 D-25, but my luthier says that previous neck reset(s) have reduced the heel of the neck enough that he does not recommend further work there. So it is actually possible for one of these to flex enough that you reach the end of the line. Thankfully, mine has great action and sounds great even with a bridge that has been waaay shaved down. Neither my 1974 D-25 nor the 1973 D-35 are even close to that point, so beefing up the structure has its benefits.
letstalkguild.com
www.kijiji.ca
