Troy,

Great question. 

Although the loft's are essentially the same, there is a small difference in the face angle at the address position.  The SureFit Tour hosel allows you to independently adjust loft from lie, but not loft from face angle as they are linked. 

As soon as you start adding loft to the 910 series of metals, you actually close to the face (and the reverse when you decrease the loft) which results in a slight change in flight characteristics such as trajectory. 

With regards to the club that is best for you, I would stay with the fitters recommendation as obviously that worked the best for you and your swing tendencies. 

Ryan P - Team Titleist

Thanks Ryan.

Just want to confirm though ... when you add loft through the SureFit hosel system,  you 'close' the face ?   My intuition is saying opening the face would add loft ?  But maybe that's not how it works, with the SureFit hosel system.   

My other thought in maybe getting the 10.5 driver (initially set at C4) rather than the 12 (initially set at C1), would be that if I did add some clubhead speed to my swing (thus increasing spin and likely launch height), that head would be more flexible, as I could then adjust to a lower loft.  But with the 12 degree initially set at C1, I could only then add more loft ?   Also, if playing in windy conditions, I could adjust loft down slightly with the 10.5, but not with the 12.     I don't know ... just some thoughts I had.  :)

Thanks so much for your time.  Appreciated.