I use a Jtek Model 3 with Centaur 9spd brifters, Shimano 600 rd and otherwise Shimano drivetrain. On another bike, I have the Model 3 with Veloce brifters, 105 rd, and otherwise Shimano drivetrain.

Both setups work flawlessly...in this case, the Jtek does "disappear" in your system. Well worth the 40 or so dollars.