Dual field bandit: going after nickels is easy. But you have to remember, that nickels are always 100% alike from the mint. Same shape, same size, same alloys, same weight, etc.... So it's easy to hone in on *just* that target. But gold rings on the other hand, are infinate in size, shape, alloys, weight, etc.... So your nickel experiment lends nothing to the "does gold sound different?" question. If all gold rings were exact in TID (like nickels are), then yes, you might say "gold rings sound different"
And you say:
"Like if a place had a ton of pull tabs bogging you down. one might choose to dig only in a certain tone range? ....."
This is also outside the question of "does gold sound different than aluminum?". This is merely the old "ring enhancement program" concept of rejecting commonly recurring types of trash. In no way is it reflective of gold sounding different than aluminum. And I might add Yes: this works when you're in a location where uniform trash (unbroken tabs for instance) abounts. But those same ring-enhancement programs can be thrown out the window, the minute you get in to a location where can slaw abounds. So you see, this too has nothing to do with the question of gold and aluminum sounding different.