Add one more to the list. Happened to me this afternoon. Heard some rhythmic squeaking during/just after some runs through the twisties, so just thought it was squeaking warm brakes - bike felt fine, running normally, and the noise went away once I was out of the canyons. While in some city traffic on the way home, suddenly heard "clack, clack, clack" and felt the bike start to buck. It took me almost a half block to get out of traffic, and just as I was getting to the side of the road, the ass end locked up completely. Didn't go down

Had to get the bike home on a flatbed. Pulley, left-side rear hub are toast, and the inside surface of the swingarm is scored all to hell. Two bolts are out, one is in, two are half-way out and bent over 45 degrees. They are threaded all the way up.
Thank God this happened in low-speed city traffic and not on the freeway :-/
I had just had new wheels, rotors and the pulley put on the bike about month and a half ago. Hmmm. I've been riding with Harley soft bags on, so couldn't see the pulley well without getting under the bike and looking for it. You can bet I'll be checking them every so often, bags or no bags, from now on.