I think it'll depend a lot on this vote; if we take the war path, then
1. we'll have another "hero leads fight with new development in mind!" that should help spread at least the courier system
2. We'll hopefully push back on gender roles, at least in war, and from what others have said, it's a hell of a lot easier with the horses we have now to use teenage or young adult women for riders...meaning that if we can get women a solid role in fighting, with a female hero in charge of things, we
might get light cavalry sooner by way of an elite female unit.
3. Even if we don't get as lucky as 3 hopes, then i predict having expanding numbers of female couriers at all is likely to spur (pun not originally intended but now that i've noticed it it sure as hell is
) our hotheaded elite male warriors into trying to outdo these upstart young women outshining them, which would in turn increase development of male horseback riding.