Sorry I wasn't more specific, the XX1 r/d uses ceramic jockey wheels. However, I've seen some Shimano parts that are plastic.
Sussed, I like the absoluteBlack chainring, particularly the fact that it's made from 7075 aluminum, not sure what the SRAM OEM ring is made from, however, I wore out one in 1 season, IMO, it should have lasted at least a few years. Luckily SRAM gave me a warranty replacement. When I'm ready to buy a replacement I will look for a chainring with high wear characteristics.