Well....I'm not so sure you'll like MY "feedback", but here it goes, because you asked.....
First dog training goes through trends. It used to be, force/beat the dog into doing what you want, then it was, NEVER correct a dog, then it went to a clicker fixed everything. More recent it kind of leveled out to utilize clicker type conditioning techiques with corrections when needed. The link you provided seems to be the latest 'trend', to not use anything around the neck, because it WILL cause aggression. Which is kind of a 'scare' tactic in my opinion, to get people to buy into their phylosophy. Its one of those statements that are 'kind of true', but not 'completely' true.
Here is what I mean.....
The statement, "Dogs are not born with the desire to pull on a leash." is incorrect. The amount of drive to pull, depends on the breed, but if that 'desire' was not there, we wouldn't have sled dogs. Yes, dogs can be taught to pull as in the example, but there are also other REASONS dogs pull. Its not just because puppies want to go exploring and we stopped them with a leash. That statement really does not give credit to the intelligence level and drive many canines are born with.
The detailed example of how a dog could interpret a handler pulling back on a leash, and yelling at it, COULD reinforce and COULD cause aggression in some dogs. But the reality is, most people are not that consistent, and not all dogs become aggressive when they are 'conditioned' like that. They are just not all programed that way, and to expect it, is wrong. Conditioning, is exactly what was described, and is used in different ways to GET a specific behavior, or to extinguish another. If that were the case it would be much easier to train a dog, because you could apply a cookie cutter technique for them all and it would work everywhere. We all know, or at least I hope we all know, that just because something works for one, does not mean it works for the next one.
The TOOL is not what fixes a pulling problem in the end. A halti, a choke collar, a pinch collar, a harness, or a Gentle Leader do not, by themselves, FIX a problem. It is the person on the end of the leash that fixes the problem, and gets the dog to understand what they want. The 'tools' just help make it easier on the person to get the dogs attention, so they can communicate with the dog what is expected. (I hope that made sense. FIRST you must get the dogs attention, SECOND you communicate what you want.) Some people/dogs do better with one tool or the other, it doesn't mean that all dogs and all people have to use the same equipment or techniques.
Now, with all that said, I am of the belief that I can learn something from just about any type of program. It may not be what they intended to teach me, or I may not use something in the same way they do, but I can usually find something to use from each training program I explore. I have even learned things that I have decided I would never use, but at least I got something out of it. Go to the class, utilize what you learn, keep in mind that there is always more than one way to achieve everything.
JMO,