Why should it be weird? The only difference between white and black bases is the black pigment added. There is no difference in the materials. Remeber base material comes in varying degrees of hardness (crystalinity). The color is just wich pigment happens to be added. Hell if the ski mfg is willing to pay the $$$ you can get any base material in any color you want.
Just remeber that sinisterd base material is always tougher than extruded.