I think an e-collar can be very useful for insurance when the dog is off leash, which is how I used it. However, the possibility of misuse is very great if the basics haven't been covered well, which is why I don't generally recommend them. You can damage your dog's trust if you use higher levels indiscriminately. With some dogs, you can also destroy the effectiveness if you overuse higher stims. IMO, it's only appropriate to use a split second tap at a high level to interrupt an action that is taking the dog into danger, then immediately switch to a verbal command or a working level stim. From my own experience, I seldom had to use the collar for recall once Perry understood, and the only time I used a high level was in a chase situation where his safety was at risk. For the most part, I used the collar for "leave it", and when he was persistent I might dial up one level above his working level, which generally earned me a baleful look and an "if you insist" reaction.
Best to teach your dog his "working distance" and to stay within it, as bird dogs are taught. They are no good to the hunter when ranging out of sight. And you can't keep your dog safe if you don't know where he is.
It's pretty par for the course for a Basenji to start pushing the limits when he matures. This is a testing time when things often start to go wrong. Much depends on the individual dog and the relationship between you, and yes, I do agree the dog should not be allowed to ignore you, but there is where experience can make all the difference. It's a fine line between enough and too much. Also between R- and P+.....
One point I missed, and that is that a Basenji is not a Lab or a Vizla, both being generally more "biddable". Basenjis are also clever, and one thing they will learn if given the opportunity is the range of the e-collar. Better not to have them figure that one out, which is another reason to keep your dog relatively close. That is one big advantage of not being dependent on the collar and having it mostly for emergencies. The less you use it and the more you build the habit of obedience the better, IMO.