Went wheeling last Saturday with some friends, had a great one hour 'til I broke my rear 3rd mount (Calmini). Though I don't think it was a faulty piece per say, I bought it used and the guy had been in a wreck with it and the mounting service had a bit of a bend in it that I couldn't get to flatten. So I'm guessing it wiggled a bit and weakened, oh well, I'll just build a stronger one. Here a few videos, in the second one you can see the rear arm break.
-Chad