The one-piece dampers outperform and outlast the original 2-piece dampers (rubber and insert). I believe they discontinued the 2-piece as a result (and to simplify the supply chain).
yup.
new ones are polyurethane I believe.
I don't think so. I think they are still rubber. Years ago, a fellow made some poly dampers (one piece) and sold them, and I put them in both bikes, and they are still like new. Less slop than rubber. (But some early ones crumbled badly. Not mine).
The maker fellow later passed on (I think). Gary something?
Shock bushing Gary?
On a related matter, years ago my wife's Ford Taurus continuously broke motor mounts (rubber). Until we went to upgrade poly motor mounts.