I can't tell you about the AT2 or the AT4, but from experience I love my AT3 Edge. For someone like me who abuses paddles in a play park and bounces them off of rocks in class III & IV water, it has been an awesome paddle. When playing in low flows, from time to time, I scrape the thing on the bottom while in a feature, it takes it like a trooper and shows little wear. I am sure that there are other paddles out there that are great paddles too, but I can say that mine has been worth every penny and after a season of abuse it still looks nearly new!
"You gotta fight for your right to paddle!"