Look for pancakes that are of the assymetrical style. That is, most of the pocket is moulded to the outside. Aker, for example, makes Flatsiders done this way. They'r not a new concept being almost as old as the first pancakes, but they are by no means standard, either.
This method keeps the holster from being pulled shut when on a belt and the pistol drawn. The original pancake patent was for a left side or right side use so was symmetrical.