I am 63 years old and last year was fitted for a TS2 driver 9.5 degree with the Tensei AV blue 55 shaft in stiff flex and MCC+4 grips with 4 total wraps, and the standard head weight and length. I have the same shaft but regular flex in my 3 wood and hybrid. Generally I hit the driver well, but there are times that I am off a bit, sore from multiple rounds, or just tired, and I switch out the shaft with the Kuro Kage Black 50 regular flex for an easier swing. It is the same length and has the same grip setup. Ball flight seems a bit higher but otherwise about the same results. Just wondering if I should be changing the head weight for the lighter shaft, and if so what to expect.