I agree that a collar is best for training.
My pup wears a collar when we go out in the backyard. He actually never pulls hard on his collar. If he does ever start pulling (which he almost never does) -- I just give him more line and pull him back in when the line is loose. A lot of my keeping him on a loose line is the way I interact with him and manage him.
And - I definitely do agree that he "pulls" much harder when he is wearing a harness. Of course, this doesn't hurt him - but he certainly isn't behaving as well.
Carol Jean |