I put a 1.5" border around the center square of my daughter's patchwork, it's been in use about a month now, and I'm always picking at it. Before I photograph it or show it to anyone I have to run the lint roller over it. Maybe there is "great black" out there that doesn't do this, but I haven't found it.
Another thought is that black might show wear by starting to fade sooner than a dark brown would.