Original.

Broke hammering out of the saddle up a short steep grade.

I believe it was the result, at least in part of improperly installing it. Gates tells you not to "roll on" the belt the way you would do a chain.
I knew that and installed it properly to start. But the belt got knocked off in the car going to a group ride, and in a rush I gently rolled it back on. It broke sometime after that.

The belt has carbon fibers inside it that apparently are rather sucseptable to damage twisting.

With proper handling I think it very unlikely the belt will break. But given that if it does it's not field serviceable like a chain, is the reason for my recommendation for a backup.

There's a thread on here when it happened that has more info.