The weight thing is pretty much a marketing gimmick. They are supposed to help the plate clamp up better at higher RPM's.
Have you ever had a clutch that slipped only at higher RPM's?
Unless I miss my guess, the weights have another, just as valuable function (which I really appreciated in my Ranger) and that is they lessen the pedal effort. It's certainly easier than the stock heavy duty 94-95 Stang combo I had used before switching. So, they're not a gimmick.