I follow Ian on Forgotten Weapons religiously... additionally 9 Hole Reviews did a good video on shot dispersion due to heating of pencil barrels that had been stabilized ... I picked an early (Cav Arms IIRC) polymer lower off a prize table at a 3 gun match, but I did not care for the design... I could not reach the mag release without moving my hand from the grip, and it had a funky stock....that is my only practical experience with non-aluminum ARs... I like the traditional 7075-T6 uppers and lowers... I think I understand them, and have built several... you don't need proprietary parts
looking with what WWSD are attempting to accomplish, if I were doing it all over again, from a practical rifle view, and not from a 3 gun game player, I think there is a lot of merit... I think that a very light weight rifle using a traditional 7075-T6 upper and lower, and one of the Ballistic Advantage or Faxon pencil diameter barrels using very small diameter and thin full float hand guards, and minimal stock you could make a top notch quick handling rifle for a lot less than the utilization of a completely polymer but expensive butt stock/lower... I applaud them for their project, I could live with a slightly heavier and cheaper platform