I think the pied gene gets affected differently by each combo based on what type of combo. Color morphs (pastel, albino, etc) don't directly affect the pied gene, they simply change the color of the animal. Where pattern morphs (cinnamons, spider, etc) can affect the pied gene and change the looks of the pied animal and make it look completely different. Look at the pied spider for example, anything but an average pied.

That sbpp rocks!!!