Well, I'm not here to "convince" anyone of anything. I'm not trying to sell anyone on anything, I'm just sharing my experiences with those that are interested. Draw your own conclusions.Over the decades, I have heard just about as many folks swear by improving their tone with an aluminum stop-bar as I have swear the same for a brass or steel stop-bar.
I'm not convinced they're either onto anything - and my Sheri sounds too good with its original pot-metal tailpiece for me to bother experimenting.
But, I'm glad it worked well for you.
I don't believe there are hard and fast rules that one material or another improves the tone of one type of guitar while another material improves the tone of a different guitar. There are WAY too many variables for that,, including individual taste. What I do believe though is that each of these materials have some unique tonal characteristics that can accentuate or manipulate a guitars tone to some degree. I think I have brightened up 2 dark and dead sounding guitars with aluminum. I also believe that I have warmed or softened a couple of overly bright, harsh sounding Fender (one tele, one strat) guitars with brass. I even believe that ordinary zinc sounds good in other guitars. Aluminum didn't sound the best to my ear on every guitar I tried it on.. The one thing I am personally certain of though is that there is a difference in the tone of each of these materials... Make of it what you will...