Having been trained in the original Fit Kit method and using it hundreds of times over, I know that the only way to an ideal set up is traveling the road to the destination. Fit Kit was based upon averaging, but was not the definitive answer as it took constant tweaking for weeks and many miles after the initial session to optimize the position. More or less, it was a starting position to evolve from.
If Retul can expedite the process of finding the optimal position, there is value to it. I have been witness to many, many "professional" fittings, including professional cyclists, but never been through one myself as I have no discomfort and am not looking for more speed, yet, I would like to go through the process to have the experience, and Retul seems like a valid method of fitting.