Personally, I feel that the harmonics of a block plate rigid to the frame are more detrimental to the internal balance issues than if connected to the block by the rubber insulators. There needs to be a small amount of damping of harmonics to aid in longevity of bolts, main caps, trans gears, etc. If I were a betting person, I bet you will find more main caps walking on plated engines than those that use motor mounts. JMO, but I do not like plates/mid plates for that reason. Like Jay said, 1200hp on motor mounts is possible, and many blown sbfs are running around with poly mounts and living. Joe-JDC.