Not a club fitter here: In general, shaft weight correlates more to torque and accuracy than to spin rate. Heavier shafts tend to help tempo, too. Lighter shafts tend to launch higher and with more spin, unless you go very expensive, as in $200 to $400 per shaft. My guess is that the shaft profile, torque rating, and flex point (high - sends the ball low, mid - sends the ball mid flight, and low - sends the ball higher) are the most important for spin rates. Save yourself some money. Find a Graffaloy 35 ProLite shaft, once a premium shaft, and then go from there. Out-of-production but a great shaft. Find it on ebay for $20 to $40. 35 relates to 3.5* torque, Steel Iron shafts go 1.5* to 2.0* torque. Most of the Titleist stock, graphite shafts for driver, fairways, and hybrids are absolute s..t, esp. at R shafts. Best stock shafts are on TE Exotics clubs. Slightly more expensive but worth it.