As somebody that has cleared every savage fight in shadow bringers I can tell you that LD is pretty bad. None of the other 3 tanks "always" require healer intervention because in the case of a buster into tank swap (E1S, E4S, E6S, E8S 1st phase) the healer doesn't need to immediately focus on the tank not getting hit anymore if it is a war,pld, or gnb. if you have a dark knight, that dark knight has to be healed for that 100% total in addition to healing follow up mechanics for the group and the new main tank. by it's design, the dark knight's skill creates "HP debt" that has to be repayed in full. Gunbreaker's basically is "costs 99.99% of your hp for a big invuln window", paladin is "free god mode", warrior is "too angry to die" the latter 3 skills are more user friendly in that the cost is either up front or come without a cost to not die during their windows. As somebody that has been a tank main for the better part of 6 years I fall into the same crowd that I would almost rather see all tank invulns removed if they can't figure out what to do with dark knight's big cooldown.