Very interesting. I'd love to try one but haven't seen one that strikes my fancy aesthetically.The tamper pad is in fact a dome, think of an inverted miniature saucer. To further the effect of the doming, I cant the tamper as I go around the bowl, further heaping the ash towards the center of the bowl.
I believe that Brian Levine, "The Voice" of The Pipes Magazine Radio Show, had a hand in designing it.