I do keep Scout on the leash when it is dark outside, and then he shows NO interest in the cats, poop, or anything else. He stands and walks perfectly by my side. It is the second he comes off the leash that the listening stops. He also always comes the first time I call him, as long as there is no poop. Generally he is a very well behaved dog.
I hadn't considered an e-collar before. I use to have one for my border who liked to leave the property, we used it whenever she went north of the barn so she wouldn't run into the road.