As soon as you get Awaked Titania, that team will be fast enough for Shingen already. Titania will be able to pick up Gaia's pace, and Shingen can bring Ambush. Against hard content, you can always bring a friend Hraes for -50% Def. Against content that isn't hard... -40% is plenty.
But it's not like Hercules will do poorly in either setup. Up to you.