I bought a one piece body for peace of mind.
I've heard all the arguments one way or another about how it makes no difference; it's better, it’s actually worse, etc, etc. I don't know, I mean I know it's all 100% mental, but just knowing that the guitar is a solid piece of wood, and that all the vibrations from the guitar are flowing through one piece of wood, not a bunch of different woods, maybe from different trees, or sections of tree that were never intended by god, or mother nature, to have sound flow threw each other, well....., it's very comforting, or even reassuring. It just feels more pure. Sort of like eating organic food that tastes exactly the same as non-organic. It's all mental, but so isn't playing guitar, and if that knowledge of what I believe to make that guitar sound better translates even 1% into my playing, well then... it's a better piece of wood.
oh and for reference, on my warmoth one piece it has hand written "1PC" at the neck joint on the body.
erik