Not really sure why anybody would choose to use this for a small dog...
I know any type of "low" setting wouldn't stop Elllie in her barking/attacking fits either. She would most likely run through it. Elllie got out of a chain link fence at our old house, and from then on it has been harness and leash.
Maybe I'm missing something, but why not use a harness and long tie out? It seems that would be safe as long as they are supervised (and they always should be while outside).