I live somewhere pretty flat, so I like deep wheels for racing, I was open minded when I bought my Reynolds SDV66 clinchers, they were a really good price (sponsored) and the weight hasn't really bothered me, I guess I am a bit of a strong man rather than a mountain goat, and prefer stiffness and aero to lightweight any day though.
My Reynolds are certainly top of the line wheels, they were a fair bit more than a new set of Zipps or anything would have cost at the time and I have had no quality issues apart from finding a lose spoke after a particularly brutal race, but they were easy to true, just take the tyre and tape off and put the spoke key in them (internal nipples). Braking has been perfect with my Reynolds carbon pads, I have no limit on tyre pressure or rider weight, and they certainly are fast, despite the 1660gr claimed weight, anything I lose going uphill is easily made up on the downhills, because braking is seriously not a problem on a good set of carbon clinchers.
As for durability, I was riding alongside a guy on zipp 404 tubulars at a tour last year, we got to a set of train tracks and his wheels exploded, 2 broken rims! This was a guy who was a climber as well, he weighed less than me.
I regularly bunnyhop train tracks at 50km/h on mine and they are sweet as, never punctured, cracked or otherwise.
Well thats just my experience with carbon clinchers, and my advice is, if you get some, get them from industry experts like Reynolds, not any of the cheap brands. You will get what you pay for.