To be exact, the Feedback feature is used exactly 0 (zero, null, none) times. However SilverBench is used many, many times each day. If you look at the SilverBench results page, you can see, that from 5 – 10 people submit their benchmark scores every day.
So no one can predict, that after 22 weeks, the one of the most prominent features will not be used even single time.
P.S. Forgot to mention, that 36 days ago we launched HTTP Response header tool. An online tool, that can be used to view HTTP header stats and information for any site in the Internet.