The following is all my PERSONAL opinion re sound, others may feel totally differently.
I spent 3+ hours today at a shop playing five different 12s. First I played the Rainsong Carbon Fiber guitar. I was surprised, I thought it sounded pretty darned good but a Taylor 456ce (with back and sides of, as the salesman and shop owner put it, "African Mystery Wood," (Ovankol) sounded better. I quite liked it and eliminated the Rainsong from the mix. Then another Taylor - can't recall the model - but it was a CE with rosewood back/sides - entered the mix. The two Taylors sounded the same but different. Either sounded equally good and I could tell nothing that would make me say that one was better than the other. Maybe the Ovankol was a bit "clearer." But my main issue was finding a 12 with good bass and the Ovankol was just as good as the rosewood.
So at that point the 456 would have been my choice because it sounded just as good as the rosewood model - the bass was essentially the same on both and I thought the Ovankol was perhaps a bit "clearer." So the cheaper guitar sounded better to me.
I then told the salesman that I really didn't want a cutaway and he asked if I needed electronics. I do but since I have added K&K pickups to other guitars, I said that having electronics already installed was a plus but not a fraction as important as having a great-sounding acoustic guitar that can stand on it's own without electronics.
So he then brought me a Martin D12-28 which blew the two Taylors into the weeds as far as a nice, solid bass. Then, since the electronics didn't matter and no cutaway was preferable, he brought me a Taylor GS 512. I spent well over an hour with the Martin and the GS 512. Frankly, I couldn't decide. The Taylor played a bit better but it was so slight as to not be an issue re buying the guitar. The difference was not enough to actually bother me as a player. But I seriously could not decide. I would play the same riff on both and one time I preferred the Martin and the next time I would prefer the Taylor. I was actually to the point where I was tired of comparing and wanted somebody to just walk in and say, "Quit screwing around, BUY THE MARTIN" or "Quit screwing around, BUY THE TAYLOR."
So then I asked the salesman to play the two guitars from about 10 feet away from me so I could hear them as an "uninterested party." That was the best thing to do! The Taylor had more "clarity" (I don't know how else to describe it) than the Martin. Initially I had thought that the Martin had a touch more bass as a player - more "rumble" against my chest, But listening to him play them, I noticed that the bass was actually about the same but the Martin didn't have the articulation in the treble that the Taylor did which seemed to accent the bass as the player but not as a listener. As a listener, the Taylor had the bass AND the articulation. So I selected the GS 512.
I'll have to install a pickup but I would have had to do that with the Martin as well. I will also have to install a pick guard since it doesn't have one. But that's OK, I'll install a clear pick guard as my flamenco guitars have. I have installed K&K pickups on 4 different guitars and think they do a decent job though NO internal acoustic guitar pickup even remotely compares soundwise with a microphone. All the pickups I have ever heard pretty much makes the guitar sound "electric" which I don't care for at all. So the GS 512s lack of the Taylor Expression system is not really a problem for me. The K&K pickup will add about 100 bucks to the price but it would have done the same for the Martin.
So FWIW, I thought the Martin D12-28 was clearly superior soundwise to the 456 ce and the rosewood version of that model. Of course the dreadnought body vs the cutaway would seem logically to me to be obvious. But the Taylor GS 512 was slightly superior to the Martin though I could only tell that when listening to someone else play the instruments. Playing them on my own I absolutely could not decide which sounded better - they seemed to switch back and forth.
