OK, the situation as I postulated it earlier is , we have two "identical " new guitars, neither of which have previously received a proper set-up, one is treated by David and the other one goes to the PLEK machine. Both guitars are played by, say, 100 experienced players , and the comments noted. If all 100 players say they prefer David's guitar then the issue is pretty much closed as far as I am concerned. If all 100 players say they prefer the PLEKked guitar, then likewise. Obviously, if the proportions of preference varies from 100% to 50% then the issue becomes less clearcut. I fail to see what the point of introducing multiple guitars would be. To me, the above experiment seems watertight, but hey, I am willing to listen and learn.