The only thing I've noticed about those "May charge without orders" units are that they don't freaking guard when I use guard mode! When a unit attacks them, more often than not, they start pushing back, meaning guard mode is basically useless to use with those guys. One of the reasons why I usually don't get those guys. I use guard mode a LOT as the advantages to stamina are terrific, and they just simply take it away.

Nowadays I stick those guys on the flanks.