Equivalent crate

I have become dimly away of an issue in the standard library maps ( HashMap, BTreeMap etc. ) which I don't entirely understand, but I think this crate solves: Also, HashBrown seems to have it's own version of Equivalent but not Comparable. Anyway, I was thinking of updating my pstd crate (which has BTreeMap etc implementations) to use this, but wondered if there is any downside before I go ahead.