I have a pair of Sidi Drako MTB shoes that I've had for 5 years. These shoes have been abused through many muddy/rainy CX races and MTB riding.
Aside from some scratches on the carbon soles, they're good as new and are by far my favorite shoes, to the point where I wear them on the road as well. One of the best $300 bike gear purchases I've ever made. My only complaint is that the fit is too snug for winter socks.
Also noteworthy that with Sidi you can replace all of the buckles, straps, tread and heel retention. I don't see any reason why I wouldn't get at least another 5 years out of these shoes.