How a particular club is going to feel for any individual is not something that can be defined. Any material that is injected, like urethane, rubber compuonds, etc. will dampen vibration. So will putting a rubber extrusion in the shaft tip. Thinner faces in hollow designs tend to sound better and feel better for most players with some kind of filler / polymer. The only thing that has a bearing on forgiveness are the mass and dimensional characteristics of the design, no matter if it is a hollow polymer filled, or a solid design. Thinner face designs can very slightly increase ball speeds, but is really only a factor in the lower lofted irons. The distance irons go is influenced more by the loft than any other factor.