I had the gt-one, its a solid aluminum piece; tracey sport also makes a solid part, that is slightly lighter than gt-one, and the replacement crank pulley provided with the gruppe M supercharger kit is solid (but steel, and heavy).
The only dampened crank pulley I am aware of is the oem, I believe in the last discussion we decided this was a modification perhaps not worth the worry, in terms of performance. There is a local member with the gt-one pulley (I sold him mine, actually), who has been running it for nearly 8 months now without issue - he claims the engine is far more responsive now, similar to the benefit seen from a lightweight flywheel on the opposite side of the engine.