The wood finish (mahogany, redwood, rosewood, bubinga, whatever) is only a very thin layer of wood veneer glued to the outside and polished to a shine. Behind that thin layer, every piano of the same model uses the exact same type of wood.
Pianos, even those of the same model and with the same exact wood finishes, naturally varies in sound. Some company allows a bigger variance than others. But the outer most layer of wood veneer by itself won't affect the sound. The amount of preparation the dealer puts into the pianos make more difference than most other factors (and it is quite possible that because of the beautiful wood finish on the outside and the associated higher price, the dealer chooses to pay more attention to the preparation of that piano than other black pianos of the same model that sells cheaper).
So don't worry about the outer wood finish -- it's just for look, not for sound.
If it sounds good to you, it is good.
Good luck.
