You watch a demo where no other software that exists or other computers are compared and find that it proves something? It's a bar graph with only one bar.
My List said "PCIE 3.0 with a real GPU"
Guess what? the consensus is that another Apple compromise was PCIE 2.0 on the GPUs. Might even be at 8 lanes. So bus speed cut in half or 1/4 so that all those nifty TB controllers have lanes.
Consensus among idiots, who cares? It's either fact or it's not, since no such details has been published, it's not.
It's pretty obvious that your list said that, but your needs are clearly different from actual users of these systems. If you can sell graphics cards your objective is met right?