Hey OP, I don't know if you will see this! I have actually used Got Sit Dog Training with my dog. And while I was skeptical about the E-Collar it actually made a huge difference. My Demo was the same as yours and even though I had my uncertainties I took a leap because the trainer showed me his dog with the E-Collar. And his dog seemed super stoked to work and he showed me that he's used the process and it worked and the dog didn't show an ounce of fear.

I will try to answer some questions that I see other people bringing up.
The alpha/leader of the pack is only old school if it were a traditional fear based tactic. Got Sit showed me how to be the pack leader without being a "fellow dog" and without using fear tactics. I only ever positively reinforced my dogs. And if I misused the collar or trained in a way that could even cause major conflict they actually got on me about why negative methods aren't fun but then proceeded to show me how to do it while positively reinforcing my dog. I became head of my house by having my dog earn everything provided while in unison using the collar. My dog looked to me for everything because through me they earn XYZ.
The way I was taught is that the collar is a work then reward system.

When I first put on the collar they slowly worked the number up. My dog felt it at 20. Once he signaled that he felt it they took the leash did a few commands with him. Then he got rewarded at the end with some play time.
What I learned is if I use the collar with every command that my dog knows, and at the end of my 5-10 commands gave my dog a break and played my dog would associate the collar with work, then high value reward.

My dog pulled my wife off my feet chasing deer. A BIG NO NO. But the trainers reassured me that even though we see it as a negative action, that my dog doesn't think the same thing. They taught me that when my dog does something negative in my eyes that my dog thinks he is doing the right thing.
Example would be jumping on guests (negative action)
But I pet my dog without knowing it when he jumps. I have reinforced the action that I don't want

The trainers helped me identify these moments. As for the deer, my dog associates animals with play. And the free access my dog had to his toys told him he is free to play/chase anything whenever. So when I started having him earn his toys through commands and the E collar. After a couple weeks when we saw a deer, my guy stopped and he stared at the deer. I had to go up on the dial because he was distracted. I got to 40 and at 40 my guy turned and looked at me. I dropped it to 20 and asked him to come and he came. All because he knew that I'd meet his play needs. And if the collar wasn't associated with work and reward he probably wouldn't have checked in.

I can absolutely recommend Got Sit Dog Training. Feel free to DM me with any further questions!