I have to say that I love to see such a nice conversation on a controversial topic. Seeing people apologize when they misunderstand... And not tear up an idea they don't agree with?
Something you don't see on all message boards!
I am not big on the alpha roll thing. It can not only be dangerous with a hard dog, but can affect trust in sensitive dogs.
But I expect both types to trust and submit (give) to physical control.
Also a submissive personality dog can, and will, exhibit dominant behaviors when there is too much permissiveness and not enough leadership. Possitive does NOT mean pemissive!
I have yet to see a dog pulling on a leash that is not exhibiting dominant behavior (at least in that situation). Unless it was pulling to get away from something it fears.
What is happening in you agility class that is causing your dog to submissively urinate? Is he afraid of anything there? Is he doing it when he is greeting?
Clicker training is great! Highly recommend it! You are on a journey that I hope you find as fascinating as I. The dogs mind!