There are three relevant sanity levels to compare against: the minimum required to function, the level where most people are, and where we wish most people were. Call these clinical (C), normal (N) and extra-rational (X). If a person's sanity level is R, then

insane: R<C
irrational: R<N
rational: R>=N

It'd be nice to have a good word for N<=R<X, but unfortunately, my intuition says that

unsane: R<<C

Which would make it an insult; so even if we redefine it as N<=R<W, people who hadn't heard that definition would be likely to react negatively.