Just had a mini-fitting of a 917 D3 at Miles of Golf in Ypsilanti and all I can say is WOW! I hit about half a dozen balls with my 915 D3 9.5* with Rogue Silver vs the 917 D3 9.5* with the same shaft on Trackman and I picked up about 10 yards and reduced spin by about 700 RPM!!
The cool thing was dispersion was better and I couldn't hit it left no mater how hard I tried - every shot was straight!
I'm going to set up a more formal fitting in January but it looks like the 917 is the real deal!
Thanks Titleist!!