I know nothing is truly impervious to destruction, but Oakley has made the claim that X Metal frames are pretty close - even claiming they ran it over with a tank. For those of you who've had X Metals since day 1, how durable are they really? The biggest question I have is re: the flex coupler. I know it loosens to the point of needing replacement, but will it ever flat out break? If my Juliets are quite flexy, but fit just fine, should I be concerned about breakage, or can I wear them with confidence? Thanks for any and all responses!