Those Pentax adapters/cables are intended to maintain the normal hot-shoe communication off-camera, so they should preserve P-TTL functionality and the related features that depend on that connection.

A simpler bracket or optical wireless setup can still work fine if your main goal is just to move the flash away from the lens axis to reduce red-eye. That can be acceptable when you don’t need every automated feature and are comfortable giving up some convenience or controlling things manually.

In practice, the extra functionality is most useful when you need fast, reliable shooting in changing conditions and want the flash to behave much like it does on-camera. If you’re shooting live action and don’t have time to set up bounced or more elaborate off-camera lighting, a bracket with a proper TTL cord can be a practical solution.

That said, moving the flash farther off-axis or bouncing it often gives more pleasing light than simply raising it a little on a bracket, when those options are feasible.