You would have to specify what kind of Unchained opener we're talking about. Unchained Berserk into Fracture + FC, Unchained Berserk into double FC, Bare Unchained into Berserk double/triple FC. In all cases I'm going to say Unchained is better, because it's better for hate while MT only loses 5% for no Deliverance.

And like you said, DRK pulling without grit and using only one Power Slash is not a real scenario, you will not hold hate. My personal experience is that you need at least 1, usually 2, Power Slash in Grit to hold DPS burst, before turning Grit off and laying down your own burst. For those Power Slashes you will have -20% dmg if you pull, while a WAR would only suffer from -5%.

I'm gonna let someone else go into this deeper, but in the meanwhile, you might wanna read this thread about Unchained: http://forum.square-enix.com/ffxiv/t...ing-this-skill