I've got a pretty good pair of Diadora clipless shoes that I've had for less than a year. But it's been a rough year for the shoes and I wonder if they aren't starting to wear out. The soles are have much more flex than they used to have and the bottoms of my feet are becoming sore and numb. I ride 5-10 hours a week of pretty hard off-road trails and wonder if it's time to think about replacing them.
My Carnac Legends are over ten years old and show no sign of falling apart. I've not paid attention to see if there's any flex that wasn't there before, but I doubt there is. The soles are thick carbon.
I expect one day a strap will break and I'll have to think about getting new shoes. Or I could do like a friend did and duct tape them before each ride.