heavens above! such big words. you're going to lose me with the old pandiculation thing i'm afraid.
language usually changes for a reason and "his" sounds crazy no matter who taught it to us at school. "his or her" is too much trouble in most speech and even writing (because we love to read a smooth sentence) so "their" sounds the best alternative. some words don't sound right at first and some do get discarded as it becomes obvious we were trying to hard. i think "their" is becoming accepted.
i had a teacher at school who adamantly taught us "his" and this grand old gentleman also objected to "okay" telling us we shouldn't use it if we don't know what it means. i looked it up and it didn't help me use the word at all. the fact is "okay" fits a slot perfectly. all this taught me was that rules don't count for ****!
on the toeic and toefl tests there is often a question about group pronouns as in "the team lost their/its way", well, either sounds okay to me but the real answer is "its" because "team" is techically singular. but if you think without grammar rules "their" refers to the people within the team.
how does everyone feel about "Ms"? i never use it, not because i don't like the idea but because it's too much trouble to even pronounce the zzzz sound. i'm not in the mainstream here so i don't know how things are in the real world with that one. i'd be interested to hear...
i also have no reason to use super polite english so i've never had "their" tested in a formal situation.
my old teacher tried to keep the status quo in the face of an unrelenting laziness. i think changing it in the face of the same laziness won't help either. ten years or so might tell which way we go!
