[BerntR]

I swing with driveloading through the ball. If the shaft is to soft I loose a club or two in distance. And I loose precision big time. So that's one of the things that matters. And it matters more with drive loading than with drag loading.

As far as shaft weight goes, I believe most golfers have a point of diminishing return. Reduce weight down to that point and swing speed will increase. Below that point and all you will get is less moving mass and less weight through the ball. I have a 65 g shaft in the driver, and it is cut to 46" so it's quite long. I once tried a 50 g shaft and it didn't give me any advantage so I'm sticking to 65. Stronger people will probably benefit from a heavier shaft. But it also depends on the length of the club of course.

It is well worth some effort to find the right shaft for the driver.