I'm finding the Sacred Band infantry to be about useless on very hard. In fact, I think I'm going to mod the name to "Scared Band." It is telling that the units that suffer the most as settings increase, are phalanx... And it is also telling that my cav deals with hoplites fairly easily on very hard.

I started using the high end infantry as a test, because I was tired of fielding an 80% cav army. My first few major battles in campaigns had been more balanced with infantry and cav, but the infantry were so awful about routing at the sight of the enemy that I relegated them to 3rd string. Looks like they are going back to benchwarming again.