hi Bill .
i am the owner of one of the 2 existing black balls set (afaik , the other owner is a player from Chicago) .
tested for 3 cushion (> 10 hours) , straight rail ( 2 hours) and around 20-30 figures of the artistic program by some A & master players. They play good enough , they seem to be less "rigid" than aramith balls. and for sure are harder to clean than the aramith balls after some play .
well, IMHO that's a good collectable set. That's why I will keep them (= not for sale)