I find that electro couplers effectiveness varies with the actual car, and the magnetic force needed to pull the coupler pin. Some cars work great, others so-so, and some not really at all. I try to weed out the poor acting couplers, by changing the trucks on the car. With the different truck and pin designs, I have a reliability of between 50% and 75%.
Coupling the cars requires a ramming speed of about 10 smph, and this still only works some of the time, again depending on the specific car and its coupler "stiffness".
I think that realistically, the sidings need to be within arms reach, as 100% reliability is not likely with the oversized couplers. Not sure about Kadees, as I currently do not use them.
