I have a few of those. Plan to put two on my green bike, which has hydro brakes front and rear. To date however have only installed on one brake on my folding bike.
Installation and bleeding went fine. Sadly I left too little hose between brake and pressure switch, making it a bit difficult to complete my bleeding. My problem (to date) is that the switch is basically too sensitive - it registers as just-about-active when the break lever is not closed at all. So when I attach it to my CAv3, it flickers like a dying fluorescent light bulb. If I take my break lever and pull it AWAY from closed, the switch reads "open" and I can ride. No good! So, I have an overly sensitive break pressure switch.
1) I bought a few of these... I can install another one. And bleed. PITA.
2) I can maybe bleed out a little pressure from the system - maybe open the bleed valve, close the brake lever 1/4", then close the valve. Create an "under pressure" start point. Have not tried that yet, too many other things to do.
For now, my brake switch stays disconnected