I'm really enjoying DRK, and its cooldowns are being called into question a lot so I wanna comment on that;
The first thing I've noticed is the massive potential uptime on these CDs. Dark Dance and Dark Mind have only 60s cooldowns, and if you popped those together on T13 with the latter having a DA buff that'd have gotten you through Flatten Breath, maybe with a Foresight thrown in as well for safety.
Speaking of Foresight, DRK not only gets its cooldowns but also gets two from each of PLD and WAR, and while BB/Conva/Awareness/Foresight are not ever gonna save your life from anything, they all had their place in endgame cooldown rotations and do mitigate damage over the course of an encounter. When you pop two of them at once you have a sorta-decent cooldown. In fact, if you stack any one of those with Dark Mind + Dark Dance, with DA boosting one of them depending on what kind of hits are gonna be more prominent in the mechanic (magical or physical) you have a very beefy mitigation tool that is essentially on a measly 1-minute cooldown. And that's without even touching either of what are considered *actual* mitigation cooldowns (Shadowskin and Shadow Wall).
DRK also has a Shield Oath and not a Defiance. And I dunno about you guys but I see Reprisal proc a LOT. I think DRK may have an innately higher parry rate, although I'm not sure. I have little trouble keeping it up on bosses, and Delirium's DK effect is fantastic as well.
In endgame content with big tank busters I see a DRK MT having to push a lot more buttons but basically achieving the same level of mitigation. They have some great self heals (imagine 1-2K DA Souleater heals o.o) as well. If you stack cross class cooldowns with the cooldowns they already have they can definitely eat some big hits.
I haven't found anyone that's wanting to screw around in old raid content for testing, but if I were to go into T13 (I'm using this as an example cause it has the biggest tank busters in the game thus far), with my DRK as MT, here's the rotation I'd use (assuming staple things like Viruses, Eye for an Eyes, and so forth):
Flatten #1 - Shadow Wall + Convalescence
Flatten #2 - Shadowskin + Dark Dance - DA Dark Mind after hit for breath
Phase 2 (This assumes only 2 Flattens in Phase 1):
Flatten #3 - Foresight + DA Dark Dance + Convalescence
Flatten #4 - Living Dead
Flatten #5 - Dark Dance + Shadow Wall
Phase 3:
Pain #1 - Foresight + DA Dark Dance
Gusts x3 - Awareness + Foresight
Sin - Convalescence
Storm of Meracydia:
Death Sentence #1 - Shadow Wall
Death Sentence #2 - Shadowskin + Foresight + Awareness
Akh Morn #1 - DA Dark Mind + Convalescence
Akh Morn #2 - Shadow Wall
Akh Morn #3 - DA Dark Mind + Shadowskin
Akh Morn #4 - Living Dead + possibly Bloodbath and a DA Souleater or two to help the healers get the buff off of you
Akh Morn #5 - DA Dark Mind + Shadowskin + Convalescence
-with Dark Dance, Foresight, and Awareness kept on CD as Akh Morn ends for concurrent/subsequent autos. Cool thing about this? no tank swap/holmgang-cover required. DA Dark Mind is OP.Also note that due to the shorter CD and the way Living Dead works, you have a degree of leeway in precasting it, and the actual cooldown doesn't kick in until the lethal blow does, which is actually a fantastic design for things like Akh Morn. So you see, if it could have performed pre-3.0 it can most likely perform now without issue, its just a matter of people getting used to the choice between 3 tanks. On top of that, DRK would most likely be doing just as much damage as the PLD WITHOUT any DA boosted hits, as keeping Fight or Flight on CD equals out to about the same degree of damage. (30% for 30s out of 60s CD comes out to 15% on average, same as 100% uptime on Darkside).