It is a curious ink. The swab looks different to the writing sample. I'm waiting until our local group's pen meet next month, hopefully someone has a sample I could try. I'm intrigued by how much influence paper choice have over the ink colour.
However, get a sample of Cacao du Bresil and see it in person. It is a lovely, complex color that toes the line between brown and grey. Only you can answer if the color is of interest, but Cacao is the single best behaved ink I've tried. I keep it in my pocket pen 90% of the time.