I'm actually new to the forum but I may can help. I was in the industry 25+ years ago. 2 decades later, all this new tech is available and 26" hard tails are all but phased out which is what I currently own. My issue originally was do I go 27.5 or 29? What I have wanted to retain is the agility and responsiveness of the smaller bike wheel size. After loads and loads of research, and a few nice guys in my area letting me take a spin on their bikes in various flavors, I have decided to go for 29er's benefit of rolling resistance, traction, and angle of attack, but find something that is going to be as responsive as I can possibly get considering the trail and wheelbase of a 29er. I started this thread(
http://chinertown.com/index.php/topic,1024.0.html ) and a couple of the guys who weighed in recommended the 062 over the 057. If your kid is coming from BMX or any kind of cycling where he is really throwing his hips around (bike follows you), then he's probably going to prefer the 062 performance.
Now this is based on what advice I have been given, but I think if you ask a couple of these guys in the forums directly it may help you. And since the 062 is less, it just may be your best bet anyway.
TJ