Does it pump more than Windwalker or Unholy? You already know the answer to that question, and so do I.
“Utility” refers to stuff you provide for the raid.
Unholy DKs offer Grip and AMZ as well as the many, many amazing perks of Death’s Advance and Spell Eater AMS in this raid.
Windwalker Monks offer a raid buff, Ring of Peace, an AoE stun, a ranged CC, and Tiger’s Lust.
Oh, and both offer MUCH better overall survivability than Outlaw does. Like, leaps and bounds better. Death Strike outheals a lot of stuff and DKs naturally have Plate armor and 10% more HP than anything else. Windwalker has Touch of Karma and either Diffuse Magic or Dampen Harm and a self-heal that is literally a part of its rotation.
And that’s the thing with Rogues right now: they’re not bad, but they’re extremely outclassed in a raid setting. Why would you play a Rogue if you could play a DK or a Monk instead right now?