Got a Tekonsha P3 for a Honda Ridgeline and a 7k hauler with one brake axle. The truck came with half the cable and the P3 had the other half. Splicing them together and installing the bracket under the dash took a morning, mostly deciding where it should go and reading the instructions umpteen times from paranoia.
When not using it, it gets unplugged and lives in the console, because it always gets juice even with the engine off. It takes 30 seconds to reach under the dash, fish out the cable, plug it in, and click the controller into its bracket. There is a power-up self test, and if the unit is left plugged in with the engine off it goes to sleep at minimal current drain.
Haven't had a panic stop yet, but the unit displays (in your choice of designer colors!) a voltage going out to the trailer brakes that corresponds to perceived braking effort. I can lock up the trailer brakes using the manual lever to check the system.