The problem with DRK MT / PLD OT is that Royal Authority has Savage Blade attached to it, so eventually the DRK is going to need to do at least 1 more Power Slash. oGCD-wise DRK is definitely better, even if we're just talking about Reprisal since it's a -10% damage debuff as well as a 210 potency hit. I personally prefer WAR pulling over both in 24mans, simply because even though you'll lose Reprisal/Low Blow Procs/Shield Swipe, you'll gain a MT who won't lose hate to anyone as well as Berserk buffed Vengeance ticks. Obviously ideally the WAR pulls and then there's a swap, but that's not happening in a 24man raid.

Anyway what I usually do is just check what the other two tanks' stances are and if they're both in tank stance then I just chill in Deliverance for ~10s. If they haven't started a countdown by then, I start mine, and pull at 0. If they pull off me, I let them have it. Pretty simple system, has worked for me every time since Crystal tower.