Earlier quoted context omitted.
Printed teeth are weaker than the belt's own teeth. Conversely, with this design the center pin could break loose and the belt would still hold, because the pin just has to stop the loop from fitting through the slot.
Timing belts are crazy strong. From my FRC work the amount of abuse and weight they will deal with is handy. Belts will burn through polycarb if it isn't tracking properly. They are strong enough to deform any pulley mount on a tight fit. Only minor complaint is that the teeth will slip if you don't have a ton of them engaged (or they are excessively loose) but otherwise they are amazingly useful.
For FRC 2010, we built four custom gearboxes using timing belts. It was a pod with two wheels driven by a CIM motor to get a crazy amount of torque to get over the humps in the middle of the field. At any time, whether on flat ground or when tackling the humps, we would always have four wheels touching the surface. The most forward and rearward wheels would only touch the inclined . We couldn't go through the tunnels because our endgame mechanic was a big hook on top that would pivot out, latch onto a vertical pole, and pivot the bot sideways using a winch. It made for an amazing photo since few teams at that first regional event were even attempting the endgame.