I too, have few problems with using “he or she” or “one” but I have always disliked the singular usage of “they”; if there must be a new term, and “hu” is clearly too risibly silly, I advocate “en” (with “em”) in the objective cases: there is already a tradition of using “n. or m.” in documents, it sounds like the slang term “’em” and it has a slight algebraic aura.

This reminds me of the person (I don’t know who en was). who wanted to remedy the lack of distinction between the questions, for which most people use “why”—“for what purpose?” and “by what cause?”—and advocated “quhy” for the former and “why” for the latter. Someone needed to tell em that the perfectly servicable word “wherefore” already exists for the former question.