I purposefully and unapologetically try to refer to everyone as "they" these days. A person's gender is rarely relevant (and can often lead to stereotyping), so I see no need to mention it every time I refer to them. And it makes life a lot simpler.
While not strictly improper, this feels needlessly confrontational and pushing of an ideology. You might find you ruffle more feathers than you think by doing this.
Some people seem not to like it (most don't care), but nothing else gets special treatment in language (one doesn't refer to people of different races using different pronouns for example - there are special titles like sir/lord/reverend, but I try to avoid those too), and I think it's good to challenge people's assumptions around this kind of thing.
