Your summary is pretty much spot-on... And as of this moment SK's are never Raid MT's. I think Guardian is it, then possibly a badass geared / played Paladin. Then Zerk / SK if they cant find even Alt Guardians that are willing to tank >.< It's a sad state of affairs imo. But yeah, from what I've experienced AND witnessed, SKs are the most "uber" group/soloing stuff tank, where as the other 3 fall into a sort of linear grade increasing to Raid effectiveness SK > Zerker > Paladin > Guardian... I'm currently on the TLE server Kaladim where gear and spells work a bit different than live, but i'm pretty sure it stands the same on that Scale.. On the TLE Zerker's just get freaking SMASHED... Like most that you see leveling up to 70 are actively ASKing in LFG to DPS instead of tank... Because thats how bad they are doing and literally cant STAND getting hit by more than 1 single mob at a time, unless of course you run 2 healers a Warder and Cleric or Druid.... It's just silly. But then Guardians on TLE are so painfully slow and do no damage, then you have the mad house SK and the really Strong Pally in between if either of them are geared they can basically just smash any content solo / with 1 healer/support..... Really silly situation tanks are in from my observations.