Black TUSQ XL is a very resonant material.  This resonance alone will give you a very full and deep sound that will amplify your tone to a whole new level.  Secondly, it's a consistent material, allowing every note you play to sound just as clear and full as the next.  In comparison, bone has natural grains which cause dead spots.  These dead spots damp balance in tone and harmonic content.  Micarta is made partially from linen and paper scraps which makes it hard to work with while corian is nice to work with but also damps sound.