I have had the opportunity to look at and test the gorget by Superior Fencing. In short, I think it is a pretty good piece of equipment, and worth the investment.
Keith Farrell teaches HEMA professionally, often at international events (why not hire me to teach at your event?), and has an interest in coaching instructors to become better teachers. I teach regularly at Liverpool HEMA, and help behind the scenes with running HEMA in Glasgow at the Vanguard Centre.