I've never felt PBT keys before, but I've heard they have a textured, almost chalky feel. I own a Quickfire Rapid, and noticed that the red WASD keys they come with seem to have a different texture than the rest of the keys, and don't quite feel like regular ABS. It's especially easy to tell if you run your nail along them. Can anyone more knowledgeable than me clarify whether the red keys are PBT, or why they feel different than the other keys that ship with the board?