no real "hard use" here, but i've been wearing oakley brand sunglasses for maybe 8 years now. all of them "o-matter" frames except one pair.
oakley "minutes 2.0"
oakley half jacket x2
oakley monster dog x2
oakley monster pup
oakley square wire (metal)
for the most part, the "o-matter" stuff is very strong and forgiving. the lenses themselves are fairly easy to scratch, and will likely be more of a burden to you before the frames will ever give you trouble. this is true though for any pair of shades though, don't you think?
i'm all about oakley's design and fit, and will continue to purchase/wear them as long as they don't change.
a simple drop will not make them snap, for sure. i've worn the "minutes" and "monster dogs" through a tour in iraq, no problems. the added benefit is they are ANSI certified protective eyewear, and much classier for the ladies.
anyhow, use them like you mean it. the are athletic sunglasses and can likely take what you've got to give. also, the US government thinks they're a-ok, as they're also issued gear (the M-frames). i never got a pair though >:-o
PS, i know i listed a lot of models that i've owned -- i never broke the frames. they are fairly dummy-proof, but not loss-proof :'(