I've seen Megan work with her dog, she is very capable of fending off strangers. However, having a reactive dog myself I can vouch for her that it gets very overwhelming and stressful constantly doing that. As sucky as it is, there is no other way to help our dogs get past their issues other than bringing them in public and anything that helps make that easier is worth a shot.
A vest/patch/whatever is not a magic fix-all, it's just an aid.