I do not know for shure but I would be concerned about durability. Tanks get banged around and could get damaged when bumped into other tanks’s sea walls boarding dive boats, transport and general handling. Bouyancy would cause a problem with extra weight on your weight belt. The weight has to go somewhere and I would rather have it in my tank making the tank nuetral in bouyancy or slightly negative. This could be overcome with weight pockets added to your tank strap but why make make your gear and setup more complicated. How well would it hold up in a marine envioment? Would it delaminate and or be damaged by the sun and the harsh enviroment of salt water? Marine enviroments are very destructive! If they are more exspensive I see them as a disadvantage.
Maybe some others with more knowlege will chime in? I would be interested in learning more.