I run a RRP metal spur and hardened clutch bell on my Revo. Not due to engine size, but my choices of running sites. I run in a lot of sandy areas and the sand tended to shred the plastic ones. Took it in to the LHS with a brand new spur, thinking it was a mesh issue. They took a look at it, and it turned out that the mesh and slipper where set fine. The sand was getting in and grinding the teeth off of the spur. Drawback to the metal is that you now have to rely on the slipper being set properly in order to protect the driveline because you loose a weak point that is easily repaired.