Alec and I had an S-Hook straighten out on us on the 6.0 at the beginning of a C-100 in a blow. Sheet in, get on the wire, BANG! Hook straightened. Don't recall it being a wimpy hook either. In that blow, not much left to do but limp into a cove while things flogged. I tend to use snap shackles a lot, but in most cases I use regular shackles now. Crew gives me crap for making sure they're tight, too.