Demon Hunter is underpowered as a class. Most of its gimmickey utility was nerfed or revamped in some way. The class needs a review itself, and maybe new features. The problem of it only comes because Soldier, as a class, offers them nothing to back up their power, unlike let's say, Spellthieves, who have bonuses to Evade/Evasion from Rogue, and even further with their ability to snatch spells and overbuff themselves.
I don't quite want to bicker much about it because the problems are pretty apparent when you play it in the game atleast once, against any other enemy setup, and you get a bad time even against NPCs. And what I think it could solve the problem is adjusting the stances to give statistics to back up what they needed, status wise, like this:
Reaver Stance - While active, grants the Demon Hunter (10 * Rank) Hit against enemies within 1 range.
Cobra Stance - While active, grants the Demon Hunter (10 * Rank) Evade against enemies who are slower than you.
Desperado Stance - While active, grants the Demon Hunter (10 * Rank) Critical against enemies beyond 1 range.
Matador Stance - While active, grants the Demon Hunter damage reduction, based on the HP difference between you and your attacker. (1% per 2% HP difference, max. 5 * Rank%)**
Now salt and whine about how broken those are to your heart's content. Be free my children!