JohnB, I have a Pac Brake and I am very pleased with it. Most threads I have read everyone that has an Exhaust Brake, no matter what brand, is very happy with it. I do not have the ECM control on mine. I have the throttle switch and do not have any problems at slow speeds. I have to take my foot completely off the throttle for it to activate. Took some time to get it adjusted that way (an hour of fiddling) but has been working great for almost a year. I also built my own shifter mounted on/off switch with a small push button switch I bought at radio shack. I didn't like the toggle switch Pac Brake supplied. I also added a small light on the "A" pillar near my gauges. I would also agree it is my most used modification/accessory.
TR