Excuse my ignorance, but I did'nt think there were great differences in Wt, compliance etc, between the Koetsu's. The distinction is sound and output, basically .47mvish, against.27mvish for the platinum. The latter had more detail and neutrality across the frequency range. I am also agnostic about body composition, having heard the Onyx and using the Rosewood Signature, I can't hear great difference. If I was paying more it would be for platinum coils, not expensive body materials.