I debate the same color issue with my paint. I know it is hard to tell in this picture, but she has the same blend in color...mapping?.....I was thinking it was the skin being the darker color under the white hair.
I have been told she is black and white....just not a true black. I have also been told she is brown and white and that she is just a tri-colored tobiano having an abvious three colors. Her mane and tail are black with some red highlights and wherever her legs have color it is black....her body is a managerie of browns and black.....If she were solid I would say she would be a dark bay. So, who knows...she is all mixed up.