Not wanting to go too far off topic, but between DNC and THF, a DNC easily either out-performs or matches a THF in every category except Treasure Hunter.
THF has a natrual advantage in Eva as pointed out, but you have to remember that you can only have so much evasion. A mob will never have less than a 20% chance to hit you. A DNC doesn't have to out-do a THF's Eva, they just have to get it to that point - which they can easily.
They out-damage a thief. You have to match like with like. Saying stuff like "their triple attack is even better with atma!" is facetious. A DNC can load the same Atmas. So a THF only has a +10% triple with max merit, which equates to 20 extra swings per 100. This is roughly equal to haste samba's collective bonus. Also, the AF+2 armor's triple bonus activation with max armor on is a 5% chance of a 10% chance (up to 30% if you stack atmas and gear). Versus the DNC AF+2 bonus which is at best a 10% chance of a 100% chance. (Since a DNC will always have a samba activated). That bonus ends up being much larger than the one THF gets.
Add on top of this that a DNC can natively heal better than even a SCH or RDM, stun and employ dmg reduction, there isn't even a contest between the two. All THF gets is TH and with the latest update, we have shown exactly how worthless large TH bonuses are.