I haven't, but I encountered a rider who did. She was carrying her bike across the 14th St. bridge, and I stopped to ask if everything was OK (thinking that the bike only needed an adjustment or something).

It was fzucked. She had been buzzing down the hill next to the Capitol. The RD had indeed overshifted and caught in the spokes, which bent a few and even broke a couple. The RD and its hanger were bent and completely useless. The rim was warped and would not clear the frame anymore, so it wouldn't turn worth a crap. The tire had flat-spotted through the cords where it skidded against the pavement. She said she barely kept it upright before being able to stop.

Don't know why she was shifting onto the big cog while going downhill, or even if that was her intent. She said that she had just gotten it back from the shop that day, too.