Under the do as I say (because I've tried all the shortcuts) clause, what I did was upgrade from another company's A-flex 12 degree driver because of ballooning and a year ago bought a 910 D2 Ilhana R-flex 10.5 of the net. When the 913's were released, I tried a 9.5 set to 11 with the S+ shaft and got reasonable good numbers. I went in to check to see how close I was. Wanted to see if one of the stock 913 shafts would be a better choice for the 910 starting at 11.25 degrees. According to the new electronic device they have, the Bassara R and the Ilhana were both producing backspin up to 4500 rpms. The S+ in R was still over 3000. The D+ and the Rip Phenom in S brought the spin down to 2200 and a launch of 10-12 when set to 10.5 but both felt heavy. I haven't had a driver over 60 g. We then took a floor model 913 D2 9.5 with the S+ in S and tried that at both 8.75 and 9.5. He liked it at 8.75 but I felt more comfortable at 9.5. According to the device, my ball was now landing softer and rolling out a lot more. The dispersion pattern was tighter if for no other reasons, the ball would fade and drop almost straght down when the rpms were above 3500.
I did use my own NXT Tour balls and not the (literally) mixed bag in the store. Wanted to keep it real world as possible. And yes, it would be better to do it outside, but we're having an early winter now in WI. All of the numbers of the fitting makes sense - except I only have a driver head speed of 85 mph. 9.5 with a stiff shaft just scares me. Should I trust the machine? BTW, the choice was additionaly complicated or simplified by a price tag of close to $300 for the S+ shaft. Trading the old driver is only a net increase of $50 over a shaft alone.