I had the same problem with mine as the guy in the first link about a month ago. My brother was shooting my bow and the arrow hit looked like it hit low about where the body connects to the legs. I saw something fly off and assumed it was a vane, but when I found it the arrow was snapped about 3 inches back and the nock was gone. I found that about 10 feet in front of the target. I guess he must have hit the metal rod that they're talking about.
As for the durability I've had it for a year and it stays outside. It still stops arrows fine and I like that I can just rotate the insert when it starts to get worn. I might have read it wrong but the AT guy made it sound like the front of his target was dangling from getting shot. He must have hit it in the same spot everytime to do that. Those things are really thick, and I can't see how that would happen.