I stumbled on a few articles GolfySpy did relating to shaft flex, shaft weight, etc. Interesting articles/tests where they have a small sample of golfers test 'common theory' of club fitting. Not endorsing what they say just saying it was an intesting read. My take-away is ... go get fitted by a good club fitter because like everything else, you and your swing are unique and just because you swing fast doesn't mean X stiff is the right shaft for you.
Anyway, if you want to check them out sometime here are the links. For me it was educational to learn a little more about how some of the things like Torque come into play and what it might really do - or feel like - in my swing.