i got fitted and my swing speed was the similar to your swing speed , i got fitted for a 910 D3 with a stiff shaft and 9.5 degrees lowered to 8.75 and i am hitting it very well with a good ball flight

I have gone through all the shafts and have a number of friends that upgraded like you are about to do.

I have two friends with the same SS and age as you and both still play of single figure HC's. They both played the 909 with Diamana Blue Board. one used the S and the other the R flex.

Both after fitting and testing different options went for the D2 10.5 with Diamana Ilima S flex (orange color shaft)  with the 10.5 loft you can set the loft as high as 12 degrees if you want more loft or you can drop the loft to 9 .25 degrees if need be.

this is a very nice light weight shaft but have the flext to give you good distance and controll.

Have fun, these are great clubs, dont go for the ego thing and select the D3 head. I am 50yrs old, ss 105 to 110 play of a 4 hdcap and played with the D2 and D3, the D2 is the club. D3 is less foregiving and lower ball flight. I know of more people that selected the D3 and changed to D2. D3 is great when you have good shotmaking skills.