I have those shafts in my 718 TMB set. They performed best for me during my fitting and took care of my needs. GG is not known for being the most capable club fitters. If you want to do an extended fitting at the TPI, you can try out quite a few more of the non-standard shafts that will require an up-charge. Titleist is not in the business of providing "watered down" options. They select great shafts that perform for the highest number of people and then invest in bulk pricing with that manufacturer. The shafts that require an up-charge are more expensive mainly due to limited availability or pricing by the original shaft manufacturer but that does not mean that there will be a significant or even noticeable difference for most players. Certainly the better the player, the more performance and even feel will be noticeable between shafts. I am not advocating for either standard or custom shafts, whatever fits the player and gives them confidence. I am mainly stating that Titleist is not going to sell a product that is not of the highest standards.