Delrin is self lubricating, so it's quality stuff. Their mounts have been used and raved about on Evo's, STI's, etc. so i'm sure everyone will be more than happy with them. The others may have a stiffer feel being metal but I can't speak of comparison's since I haven't seen them side by side. I'd expect the Delrin to last longer being self lubricating given their Delrin composition.