It would seem to me that the My Wedge and your standard transom savers are of such different design they are each hoping to prevent different problems. The My Wedge in no way, shape, or form does anything to protect your transom from the weight stresses put on your transom from a motor, it does though help protect your lift/trim hydraulics from having to endure the abuse of a bouncing motor. I suppose it being rubber the shock absorber effect is in play, but the transom is still supporting the full weight and torque of a non-vertical motor.
The transom saver though does actually transfer some of the engine's weight (shouldn't be much though) and nearly all of the torque inflicted on a transom to some stable point on the trailer frame. In order to properly use a transom save though, one must also snug the boat to the trailer using transom straps. Otherwise you may be defeating the purpose.
At least, that's my take on the physics at play with these two tools. I use the transom save on my Lund with a Yamaha motor, but the Toon's Mercury is left hanging on the Toon's transom, in a near vertical position. Maybe I should get a wedge for it as there is no place to mount a transom saver on the Toon/trailer combo.