Just wondering if anyone has tried both. What are the pros and cons? Has anyone weighed the two? If so, which one is lighter? The thing that I guess bothers me about the RM bearing deal, is if the steel thrustwashers break easily, then wouldn't aluminum break easier? What's the best setup for high compression/high rev applications. I don't want it to be a ticking time bomb, but I plan on frequent top end checkups, so reliability isn't the only factor I'm weighing.

Why are you considering a YZ piston when you can still buy pistons that are made to fit yur engine without any modifications?  Re-pinning the ring end gap is expensive and is never as reliable as the original pin installation.

High performance two stroke engines require frequent tear downs, inspection and piston replacement.  Pistons ware/collapse, fatigue, crack and then break.  It is up to each owner to tear down and inspect their top ends frequently to determine how often your engine and riding style necessitates the piston to be changed.

It is not uncommon for guys to be able to replace the piston 3 or 4 times on the same bore if you keep dust from getting past the air filter and run a lot of oil in the fuel.