So this thread inspired me to take a look at the 9000 cables installed on my 5700 group set. Cables have about 4500 miles on them. The front cable looks like new (I don't do much front shifting) but the rear is badly frayed. Bad enough that I'm afraid to ride the bike before replacing the cable. It's worse on the middle of the cassette where I spend most of the time, and less bad on the least used gears. I'll probably have them replace the inner cable with a non-PTFE coated cable. I hope it doesn't degrade the shift quality too much. The 9000 cables shift really nicely...