Quoted from chad:
Same with early Ster solid state games like Catacomb.
I have a Seawitch with the metal pop-bumber rings and a Catacomb (a year newer) with the plastic pop-bumber rings. In my experience, the plastic rings are just as durable as the metal, and comparing the Seawitch and Catacomb side-by-side, the plastic rings being lighter seem to give the pops a more responsive action (ball seems to fly a little faster). This is one of the cases where I would keep the game original and not treat the "cheap" part as inferior.