Before we tried hitting the 917, we were informed of some of its characteristics in "FAST". It's true and it proves itself to be the driver that should be in your bag.
Fast- launching keeping to its ball speed at an optimum launch angle longer.
Adjustability- Surefit
Sound (it's symphonic, I think)
Technology- Construction and materials.
So my 917 came in and I did my own testing over and over, and time after time, the 917 exudes all the FAST characteristics, closer to my target, longer carry and roll. The 917 rules and it's in the bag.