I just used a wac'em on a Javelina. Two of the blades bent, one of them folded almost in half. Thankfully it penetrated through to the other side and killed the animal very quickly.
This was the first time I have shot an animal with a wac'em. It really surprised me to see the bent blades, as I have shot many of them with Thunderheads and never bent a blade. They do shoot great with carbon arrows.