I've seen only one. It was mounted on a bike a customer brought into the shop. This bike had all the toys, Ti bolts, ti this, ti that... Top of the line everything. The only thing it did not have was any signs that it had been ridden at all. No scratches, no mud in fact no dirt any place on the bike. IE Poser..
The shifting was positive, but for 1600 bucks I can put up with cleaning and replacing cables as needed.
"When the spirits are low, when the day appears dark, when work becomes monotonous, when hope hardly seems worth having, just mount a bicycle and go out for a spin down the road, without thought on anything but the ride you are taking." - Arthur Conan Doyle