Well I think the string path is a crucial part of a guitars tone. And things like locking bridges, locking tailpieces, and the material they are made of directly effect the sound. Even changing the saddles on a bridge and leaving everything else the same changes the sound. The question was more along the lines of people who have used both metals, what changes did they notice. If you're of the fundamental belief that if your guitar stays in tune then dont mess with it, then more power to ya. But if duct taping a hotel's front desk bell to my headstock made my guitar sound nicer, Id do it in a heartbeat.
And who cares what Eric Johnson can notice anyway? :D