I believe Dave Pelz's company started the Featherlites in the early 80's. A few tour players used them. I think D.A. Weibring may have won a tournament with them.
I did hear from a former tour player that most of the guys using them had lead tape all over them... so they must have lacked something... MASS. They were OK out of good lies, but did not have enough MASS to be good out of heavy rough.
Now... concerning the MASS of the player. There is a theory that if TENSION is introduced into the player during the swing, especially IN THE ARMS during the downswing, the player will be taken out of his CORE, and strike the ball ONLY utilizing the weight of his arms, rather than the MASS of his entire body. Do you think there is something to this? It seems to me it may have some merit, especially with Rope Handle Techniques.