After messing around with flightscope, i found that to maximize distance you want two things
1) higher launch angle
2) lower spin rate
The problem is launch angle is determined by the dynamic loft, and angle of attack. Roughly 85% D.Loft to 15%AA
So if you hit down on the ball, your lowering your angle of attack by 0.15 degrees per degree down. That can be alot for an amateur who hits down at 5-10 degrees. That means a lot of distance, one degree down, could mean as much as 5-10 yards in some cases, depending on other factors
Dynamic loft is based on the swing. Swinging up on the ball naturally gives a person a better dynamic loft condition. Hitting down will tend to create conditions were the spin loft is increased, and this is why you see amateurs hit those ballooning shots. The ball starts off low, then rises up, and falls down at a steep angle. So loss of distance and no roll. If you shallow out that angle of attack, get it to slightly positive, now your swing will produce a lower spin loft.
Basically were looking into a range of launch conditions were you don't want to low of a loft because you'll loose carry distance, but if you have to high of a loft your bringing in to much spin, and lowering your smash factor.
This is were different aspects of the golf shaft come into effect, mainly the kick point. If you have a high kick point, that will lower the launch angle. How will this happen, it lowers the dynamic loft. You can get more fine tune on this by getting a high kick point, but different tip and mid section stiffness as well.
Once you get your golf shaft tuned in, then you can see what loft you want. So basically loft on your driver is fine tuning were you want it to be.
But, by looking at trackman figures, you probably looking at a spin loft of 8-13 degrees. I would say that lower swing speed want to be near 13, higher swing speeds want to be near 8. The reason is, higher swing speeds will produce more spin, so they want lower spin loft. While slower swing speeds can't count on the launch angle to produce distance like higher swing speeds, so more spin for them will mean more carry.
Titleist has a good reference in there custom golf shaft guide. they have a good chart showing launch angle versus spin rate. So you can look at your current golf shaft and say, Ok is the ball ballooning, is it launching to high, so this is my current shaft, here's one that might better.
Your not going to get pro level accuracy, unless your willing to shell out money, but you can get close. With and adjustable driver, you can then fine tune the loft down more.