You can have drivers fitted these days so if you get the opportunity do so. You will learn more about shaft flex in 50 minutes than you will in ten years of playing golf. 3 years ago i used a Callaway Big Bertha 9 degree with a stiff shaft. I was fitted with a Henry Griffits HG400 10 degree with a shaft which is in between medium and stiff and as well as hitting it higher as you would expect i also hit it 30 metres longer. The biggest difference i have found is that it is all carry so i lose no distance during winter. The in word now with drivers is launch angle.