I’ve just read the best advice I’ve ever seen on this subject in Bryan A Garner’s book The Elements of Legal Style (2nd ed., OUP 2002, p.207). It’s worth quoting at some length:
Gender-neutral language isn’t about political correctness; it’s about credibility. Regardless of how you may feel about the old “rule” that the masculine he includes the feminine she – whether you detest it or you like it – you’ll need to handle the English language with some care to have credibility with a wide range of readers.
This isn’t an easy task. On the one hand [some] readers …. will think you’re crazy if you write he/she, s/he, or (s)he. They’ll know you’re crazy if you write – as one book author has – s/he/it. On the other hand, [readers of a different sort] will think you’re a troglodyte if you use he to refer to readers generally – as if the feminine were the unstated exception swept into the masculine rule of our language.
Is there no way to win over your readers, then?
Yes, there is. It takes some skill and a lot of effort. With those two things, you’ll be able to produce a style that never induces readers to consider your personal biases. If your point is that you want to induce this reaction, then you’re rebuffing some of your readers – something you may willingly do unless you have a client whose money and perhaps even freedom are on the line. If you’re trying to persuade someone on a point unrelated to sexist language, then the issue shouldn’t even arise.
Garner goes on to demonstrate various specific techniques: weeding out pronouns (e.g. ‘a claimant in this situation should do this or that’ instead of ‘if a claimant is in this situation, he should do this or that’); pluralising (‘if claimants are in this situation, they should do this or that’); using the 2nd person and imperative voice (‘if you are in this situation, do this or that’); and several others.
But his key insight is that – if you are writing on someone else’s behalf, and seeking to persuade – it doesn’t matter whether the feminists or the troglodytes are right. What matters is that if you side visibly with either, you’ll risk annoying someone. The only way to be reasonably sure not to annoy any reader is to make the issue disappear from sight.