When I used to walk my girls together, it was always trouble if another dog barked at them. Wanting to get at the other dog, and unable to do so, they would attack each other (transferred aggression). It was never serious, but certainly was a nuisance! Most Basenjis I have had are a pain when they see something interesting, although when I bike Perry I find I can usually just speed him past any distraction. (if other bicycles pass us, boy does he go! Gives me quite a quick ride!)
I find it so much more relaxing to take him in the fields loose. When a dog is on a leash, he knows exactly where you are and doesn't pay you much attention. Off leash, I find Perry keeps an eye on me and isn't comfortable getting too far away. I reinforce this by hiding on him if he is distracted. It's a good game, and results in him watching me more closely, to the point where it has become difficult for me to escape his attention. If I do manage to hide, he checks the area where I was last seen and once he spots me he comes like a bullet! Great to improve his recall. :)
It is certainly possible, with training and practice, to obtain a loose leash walk from a Basenji. But it's a lot of work!