I'm a firm believer that the Americas were much more populated and advanced than previously thought. I think there is enough evidence to put the Clovis first hypothesis to rest, although I haven't seen any convincing evidence that any pre-clovis civilizations were particularly widespread. But looking at those images, I can't help but think there is a strong possibility that those scientists are reading more into the data than it says. I'm not saying I don't think it's a possibility, but prehistoric anthropologists seem to be pretty clanish and not welcoming of any hypothesis that contradicts their beliefs. More so than most branches of science, for whatever reason. Maybe it has something to do with funding and some kind of intense rivalry on who can come up with the best solution to the questions.
It would be pretty cool to see those hypothesis validated, and I'm rooting for them, but I'm skeptical. Of course I'm saying all this without having actually spent some time looking into the data, so I can't entirely discount them either.