As the other 2 mentioned, it would be nearly impossible to break one under normal (or even abusive) use unless you actually tried to break it. However there has been one damaged during shipping, but it was 100% my fault, and quite stupid.
I bubble wrap the fronts before shipping. I wasn't thinking straight and put the waveguide down on top of some hard stuff. Well, I do that all the time, but always leave room for the cardboard box to get smashed down a bit during shipping. But with this package I used a cardboard box that wasn't quite tall enough. So the rear of the flange was touching the inside top of the box, basically having to hold up every package that they dropped or sat on top of it. It could have been under 400lbs of other boxes. Or they could have dropped one of my 60lb flat packs directly on it while loading them in the truck.
But as long as it's not used as a 400lb jack stand like that one was, the waveguide is plenty strong for a compression driver. I had a 5lb CD bolted on the back and screwed to a speaker enclosure that tumbled end over end from a good 4-5 feet in the air. Nothing broke. That was good enough for me.
If you smacked one with a hammer, I would guess the matte would crack before the gloss would. The matte uses a harder plastic, the gloss uses a smoother plastic that would likely have a bit more bounce back if smacked really hard.Edited by Erich H - 4/27/13 at 8:33pm