TSS may indeed result in more people dying in accidental shootings. The 9s are gonna penetrate about like lead 4s, but there will be more of them, and they will make a smaller wound channel. I would think they would probably be a wash compared to lead #4 as far as lethality to a human.
But the TSS #7 could certainly kill people at a much higher rate than any turkey load used before. I think it would be a good idea to make #8 the largest legal size for it. There is no excuse for mistaking someone for a turkey and shooting them, but idiots will be idiots.
I suspect Federal is gonna eventually face a lawsuit for selling these shells in #7. Someone is going to wind up dead when they would have survived if shot with any other turkey load.
I once had a guy crawl up on me when working a turkey on the Coosa WMA. And when I yelled at him he refused to acknowledge me and set up on the turkey. I let him have the spot, but it was unnerving.