I have heard of crosses, but don't know if the reports were accurate. They may have been just slightly different colored individuals. If you are trying to get a pair to breed, why would you consider one of each type? Your odds of a successful pairing would have to be much lower. If there are successful crosses, I can't imagine the young looking enough different to be especially valuable in any way. The true perculas seem to have a higher value, especially those with more than the normal amount of black, from what I have seen.