I'm going to agree with hakukani on this one. I tend to believe that the majority of sound is created with your oral cavity and mouthpiece. The reason different materials of ligatures can make a difference in response is because a reed actually vibrates and that actually creates sound. A neck however, does not modify the sound by vibrating. You can make a neck out of metal, wood, plastic, whatever, and it will still sound similar. Variations will be in small differences between the necks. I tend to believe that aftermarket necks made out of special materials don't play better because of the material, but because of design differences.