As an engineer just looking at a plastic "wad" tells me that this has to be the biggest advance in cartridges since paper, it screams low cost / high tech, I doubt there would be enuf heat to melt the plastic at ignition as pressure would do the launch from the rear of the cartridge long before the burn arrived and even the longest barrels wouldnt create friction / heat that quick.
I have been lucky to shoot at Bisley and invited twice to compete in the ASSAM shoot @ Barry Buddon so I can shoot BUT was allways poo @ pistols and my shotgun aint that much better so I would be lying to say I could notice any difference between plastic and fibre on how many birds or clays I hit BUT just perhaps the folk that "test" and report on anything from cars to cartridges might be swayed by the manufacturers to sell the product with the biggest profit?
What really scunners me is seeing spend cases left to rot, lazy bastards them.