Just spoke with the lead of the Tesla team that did my install a few weeks ago. He said they had not received the new underlayment at that time but I got the impression they are using it now. Said they made the switch for two reasons: 1. They do not need to overlap and can put it down in single ply; and 2. It has a texture on it to allow them to move around easier. I think we had guessed the second reason. The first one probably saves them some money and may give a more uniform look on top of it. Asked about the "no residential use" issue. Will post any response there.