I recently attended a local club fitting to look at the 910 Driver.  I told (and showed) the Titleist rep that my irons were old and heavy (Wilson Gooseneck, Dynamic Stiff shaft) but I still hit them solid and straight at age 60.  My 5 iron carry is about 180 yards.  My swing can get fast and I feel the heavy clubs keep me slow.   He had me test a variety of shafts and settings on the Driver.  There were other people there of course and things were a little bit confused, but manageable.

The end result that he recomended was a  Diamana 'ahina 82, S with an A4 setting.  He said my swing speed was 94 MPH.  I was hitting the ball about 225 yards.  I was absolutely thrilled to see how straight I was hitting the ball, but a little disappointed with the distance relative to my iron distance.  I went to a local retail outlet and they did not have the Diamana 'ahina 82 and had me hit the Kali S with a stiff shaft.  They had my swing speed at 98-103 MPH and ball travel at about 240 yards, which is a distance I know I sometimes reach with my current driver.  However, the club felt light to me and I hit some duck hooks, etc, just like with my current driver (Big Bertha, steal shaft).

Should I expect such a large difference in swing speed for the 17 gram weight difference?  How much is the shaft characteristics affecting my ball flight, ie hooking vs not hooking? 

Any thoughts would be appreciated.

Nick