Using "secret" in that sense instantly reminds me of hyped-up headlines for time-waster news stories. Most people don't know what 2^8 is, either.
this here is something that's pretty useful to most ssh users, yet seldom spoken of
a better analogy would be comparing it to calling a very good, but not well-known restaurant a secret place - using the word to mean a hidden gem rather than an intentionally hidden secret