Yeah, aluminum (or any material, really) can fail just as suddenly as carbon. I find the "catastrophic carbon failure" stories true, it's just that they're overreported compared to other mtb parts failures. Not sure about bars and posts, but carbon frames will generally let you know before they go. They creak, and if you ignore it long enough, sure they will fail in a more exciting way. I am running an Aerus mid-rise over-sized bar on my Enduro, which I regularly do 3ft drops on. Also have a friend using the same bar. No problems yet. I have another friend who has broken at least 3 seatposts, all aluminum. Each failed quite suddenly.