When we got our first GSD's, decades ago, I had no clue what I was doing. We hired a local trainer recommended by the local pet shop. She was great for about four months and that was that. She was way out of her league once these dogs turned about six months of age. They were assertive and smart. I knew nothing at the time and still knew we needed a different approach. No amount of clicking and treats was making a difference.
We were about to have our first kid. My requirement was simple: A kid should be able to reliably walk the two GSD's simultaneously without a leash. That last part is because, if you can achieve that the leash simply becomes a formality. An out of control dog on a leash can be very dangerous. Never mind strangers, a 120 pound GSD can make an 80 pound kid go flying if it decides to bolt after another dog, or worse, cross the street.
We got another trainer someone recommended for more assertive dogs. The guy was a complete asshole. Violent. No. He lasted a week.
I don't remember how, we finally got connected with a Schutzhund community and ended up hiring this young girl (21 at the time) who trained GSD's for all aspects of the competition. That's when I finally went to "Dog Training University". It was amazing. I learned so much.
Yes, we used slip collars and e-collars. NO! They are NOT torture devices. Anyone who uses them to hurt the dog has no clue what they are doing AT ALL. Properly used they are no different from touching the dog or a gentle tap. In particular, e-collars are one of the most misunderstood tools. This is terrible because it is actually the best tool by far. Again, properly used. If anyone is interested I can certainly expand on this.
Our dogs went from being almost impossible to control to being able to walk off-leash just about anywhere without any issues whatsoever. The level of attention and obedience was almost incredible. Here's a simple example: I could go to a busy dog park, tell them to sit-stay, walk hundreds of feet away from them and they would stay there no-matter-what. Somewhere I have a video of a whole gaggle of dogs running in circles around my two dogs sitting under a tree while waiting for my command from the other end of this football field sized dog park. From that distance I could tell them both to lie down, sit up, advance (one at a time or together) stop, lie down again, or run towards me. And no, these dogs were not "dead" or beaten into submission, in fact, they loved to train so much we did it every day (which is what it takes) for hours (I worked nights back then).
Since then I have trained many other GSD's. Not at the same level, I just don't have that kind of time any more. We currently have three GSD's. They are very assertive. They are not pushovers. However, when my little girl was seven years old she had full command of them no matter what the situation.
That said:
I am very familiar with Michael Ellis's methods. Being that this has been a hobby for decades I have consumed a great deal of material from top trainers. He is one of them. I own a bunch of his DVD's and books.
I would definitely recommend Michael's methods for most house pet dogs. If applied correctly you will have a very well behaved dog. Getting to that level of full off-leash control requires a tremendous amount of work, regardless of the method one might use.
The caveat with regards to Michael's --or any other method for that matter-- is that they don't tend to work very well at all for dogs that are on the assertive-to-aggressive (or potentially aggressive) scale. Have you ever tried to stop a person who is in full rage mode just using words and positive rewards? I don't think there's anyone alive who has done this successfully.
We must not humanize dogs. They are animals and, as such, capable of some pretty horrific behavior. They are not kids that you can fix by cuddling-up with them. In fact, stuff like that will ruin a dog more often than not. Dogs understand, want and react well to structure. Provide that and they will thrive. Provide chaos and you'll end-up with problems. One of my current GSD's is big and super-strong and assertive as hell. Pure breed and bread to work. He would fit very well as a military or police dog. And yet we have full control. Happiest dog in the world. You'd never know the level of training he has except when my daughter can make him stop, sit, down, approach, retreat, etc., without saying a single word.
One of my absolute favorite series of books and methods are by The Monks of New Skete. Regardless of the breed you own, these books should be required reading for dog owners.
Here's a fun look at Schutzhund (my dogs could do all of this and more):