I haven't tried the FTZ setup with the pinned YZ-250 piston but I have heard feedback from those who have. The biggest complaint is the tiny pins falling out which lets the rings spin around & catch a port. When that happens, not much else matters. As far as weight goes, I couldn't tell you which is lighter. Now on my zilla, I run the RM bearing with billet aluminum thrust washers & have never had any problems in the 3 years I've been running it. Some guys here spin their zillas up to 9,000 rpm & have no issues with them. But a YZ-250 piston would not fit a zilla either, it's just for the LT-250Rs.