I've posted my theory here before: I believe that weight is proportional to the amount of spin needed in order for the disc to achieve it's behavior/potential. I have tested (and written about) the experiments my friends and I have done on football fields with a wide variety of discs at different weights and plastics. Measuring pretty exactly how far they went, how they flew, the flight of each path, etc. Then did Excel wizardry on the whole data set.
Out of all this I believe that weight mostly affects the spin you need to put on the disc. The lower the weight, the less spin required. The reason "weaker" arms or beginners are encouraged to use lower weight discs has nothing to do with the strength of the arm. It has to do with their not having learned (yet perhaps) how to impart high spin on a disc at release.
As a concrete example, I bought 2 175g Boss discs, back when I thought I just needed faster discs to go farther (I throw ~300ft). The Bosses *always* hyzered out early, and I grew to hate them. I bought 2 150g Bosses, and began to get decent distances out of them. But sometimes they would turn over too much, and I didn't have enough control. This is because I, personally, don't have that much control over the amount of spin I impart. Sometimes I get great snap, sometimes I don't. The lighter weight Boss was greatly affected by this variance.
I finally settled on a 165g Boss, in R-Pro plastic. I still have a lot of variance in the amount of spin, but now my *best* spin just sends it into a bigger S curve (it never turns completely over into the ground) and my weakest spin has it go flat into a long slow hyzer. Both acceptable. And when I hit the sweet spot, then I drive ~375ft. Which is excellent for me.
Again, I've put a lot of analysis into this. Doesn't mean I'm right, but it's going to take a really strong data-driven argument to convince me otherwise. I think for each arm you want to learn your range of spin you impart on a disc, and adjust (typically lower) the weight of your discs until the average spin you impart is best for that weight. I've done this by slowly lowering the weight of almost all the discs in my bag (all now in the 160s, except for a few heavier ones for windy days, or special occasions.)
I also believe that what separates the pros from the amateurs is not arm speed, strength, or raw speed/power/spin. What makes them great is the ability to impart the amount of spin they know they need so consistently. They may not realize it, and certainly it is all through education, muscle memory, and feel, but I think that's the key to great golf. Imparting the correct amount of spin consistently so that you get the flight pattern you're looking for.
My $0.02.
