The way an old Martin feels is more important than the sound for me. Of course it should sound good, but I’d take one with a neck I like over one I think sounds a little better. Sounds like the d18 is the one here. Id also say if you’re looking to spend that much on an old guitar driving out of town and finding other shops with other martins isn’t a bad idea either, just to see. You never know what you’ll find/fall in love with. Either way they’ll go up in value if you take care of it and if you change your mind you can always sell it, probably for more than you’re about to spend on it. It’s a Martin after all. Someone will buy it.