The abovementioned Mercedes timing chain is double roller and there were grooves that didn't look as ragged as the pictures. After around 90K miles everything was quite smooth and it sure looked like the wear had stopped or slowed way down. As I had already bought the new banana rail I installed it, but wouldn't have had to. There was still quite a thickness of plastic under the grooves.
One other thing, wear probably slows down when the chain has worn in a little and there isn't quite so much pressure on the tensioner. But I'm sure the "silent chain" would wear a lot less on the plastic.
R.