3K plus on mine, not so much as a quarter-turn of an adjuster needed. I use mine to run Campy shifters against a Shimano drivetrain. Perfection.unit said:+1 on the Jtek.
I was skeptical at first, but it works very well (only have a few hundred miles on it so far).
I would be interested to hear from people who have many many miles on one, but it would seem that there would be little wear/diminished performance with an aged Jtek.
One other plug for this gadget is the cost savings you get with Shimano cassettes. Perhaps the Campy durability is better (I do not know), but the lower cost of a Shimano cassette vs. Campy is very attractive to me!