It has been an interesting discussion to read. Myself, I don't know, right now I think, if I need to hold them for law enforcement, I can tie them up AFTER knocking them out.
I`m a big guy and I trained jointlocks and restraints for years. But I still wouldn`t count on just restaints against a bigger stronger opponant. The most effective "submission hold" is a knockout.
And your first duty isn`t to hold onto the badguy until the police arrive to give you a pat on the back and the keys to the city. (Nice fantasy, truth is usually you just ride to jail in seperate cars.Cops like to let the lawyers sort things out.) Your first duty is to get home to people who love you and depnd on you. Second is to be a good witness and call the cops after you`ve gotten away safely.