I made a set for my bench vise at work, and like them. Had seen copper jaws on YouTube etc. (Tom Lipton, probably) and was curious to see how it compared to aluminum. We didn’t have any stock heavier than 1/8” copper, so I silver brazed that to some brass.
To be fair, this is a light vise that gets used for filing, deburring, picking broken taps out for coworkers, etc., often on finished parts. (I also have the luxury of two heavier vises within 25’, if I want steel jaws)
I do like that the jaws are fixed, and can’t wander off.