@Mantis:
do you guys do this if there are other people around? how do they react to listening if another person is in the area with you?
There were a couple of times when other people appeared in the area of the park that we were letting our B's roam at. The B's ran over to investigate/say hi, and fortunately, they weren't anti-canine types. The "come" command won't work in that situation, since our B's are too curious. Their thinking is: "I'll get the salmon treat after I say hi to this stranger, who might also have goodies for us."
Life is not risk-free for any creature or human that walks upon the face of the earth. My view is if risk can be properly managed for the sake of allowing good experiences, it makes life more worth living. I would add that we feel very fortunate to live near a very large, virtually vacant park surrounded on three sides by water. We would never attempt this kind of thing in a regular city park.