I'm using nylon LCA from firmfeel and their greasable pins. Don't know if its a listed item. If not, tell Dick you are autocrossing and thats your interested.
They do add a little vibration to the steering wheel on certain highways,
The advantage over polyu is they will not plastically deform - which is possible when running road race or autocross compounds.
If you're looking to reduce every compliance point you can, and some of us go there, then nylon over rubber is another small gain.
small - the rubber isn't that thick or that compliant - but a degree of camber under load in competition could be worth it...