Torque, feel and accuracyIt's gotten less and less simple as shaft manufacture has gotten more discerning. For a while performance was associated with tighter torque numbers, just as for a while you could tell how raceable a slalom ski was by how hard it was to twist in your hands. Now, it's much more important to have a proper torque progression and proper balance between torque an longitudinal stiffness progression, just as with modern skis.
The biggest effect is actually on feel - softer-torque clubs will feel smoother and more solid at impact, stiffer ones will feel snappier or boardier. However, how a club feels as it loads and unloads will have a huge effect on performance. A too-stout (or too light) club which doesn't allow the player to feel the load at transition will tend to get pulled left as the player tries to feel the shaft. A too-soft club may either hook of flare out to the high-right. A manufacturer can create a very stable, low-spin shaft by creating a stiff tip section, and then moderate the feel by allowing that same section to have slightly looser torque than normal - the MCC Ozik Altus would be a great example. A slightly older design like the Grafalloy Blue or even the Accuflex Evolution had low spin due to tip-stiffness but horrible feel because the torsional rigidity was so tight
It used to be the case that the high-launch, high-torque shafts were all pretty high-spin too, but with new geometries that isn't the case anymore either - it's possible to build what amounts to a hinge into the middle of the shaft to achieve high-launch, while retaining tip-stiffness to reduce spin. (There's a lot more to low-spin than tip-stiffness, but no-one asked for a dissertation :^)
One thing, though - there's no standardization of torque measurement within the industry, so you can't realy compare a Mitsubishi to a Graphite Design just by manufacturers' specs. I measure all shafts in my shop on my own jig, so I have a personal record, but it doesn't really translate directly. Pretty funny what the readings actually are sometimes.
If anyone has questions about the perfromance of a specific shaft feel free to drop me a line - I've worked with most of them, and I hit most everything I work on.