Unlimited Fiberglass

I have our members aluminum brackets on my Duster and they are very light in weight but thick enough not to be a sloppy mess. Bendable if need be.
IMO, a total win win.

IF you are building a "Race Car" and every last ounce of weight reduction is needed, then the glass units would be better by a small amount. Enough small amounts of weight add up and quickly when the list is done being tabulated!