I know the Easy Walker harness is just a regular harness that clips to the chest instead of on top at the shoulders. By itself it still works as a regular harness in putting nothing but your own physical strength against the dog's for direction/correction. Combining it with a regular collar where the leash is clipped to both I'm confused about how that could work without a special leash that has two separate lines for clipping... if the harness is clipped at that chest and the collar is clipped at the top of the neck, how is that even possible with only one clip on the leash? The only way I can see that to be possible is if the collar is waaaay down on the neck close enough to the chest to clip to both which isn't where a collar is supposed to be and still gives no head control. Is some kind of special leash used with two clips to attach to both the collar and the harness so that both are worn on the dog in the right place? And where the correction applies only to the collar and not the harness?
In looking at the Easy Walker harness site it still looks like nothing more than a modified regular harness that still doesn't give head control and puts you having to use your own physical strength against the dog's. They even say it's for "gentle" correction, which would only work with a dog that pretty much does what's asked anyway... the bigger the disobedience the bigger the correction needs to be, and if you can't give a stronger correction with this thing (and I'm not seeing how that could be) it's pretty well useless. I'm not seeing how this thing can give any correction at all by itself.
Combining the harness with the collar makes more sense because at least the collar gives you some control of the head, but I'm not seeing where the harness part is even necessary without a special dual clip leash... actually I still see the harness being superfluous and more of an added problem than anything else. A harness/halter (two names for the same thing) isn't designed to control the dog at all - without control of the head it simply can't. Whether clipped at the chest or on top at the shoulders it still give no control of the head and puts your physical strength against the dog's as the only means of control.
The snout piece (a forging collar) works well because it can give even more control to the head especially for a dog that pulls on leash. The harness though is just a useless expense that really only adds problematic issues. It's simply the wrong tool for controling a dog because a harness cannot control a dog and was designed for non-control for those dogs that do certain jobs that controling the dog is not wanted. Companies and stores that sell them only sell them as a tool for control when they aren't because they cost so much more than a collar.