It's been quite a long time but I remember Boomkin at ilvl ~595 being brutal. Any spec that has too much ramp-up time or no burst-AOE after they've already used their CDs to boost their single-target instead will find getting Silver obnoxious until they get the exact pattern down.
For Windwalker, Frost DK, Frost or Arcane Mage, and Elemental Shaman it was kind of a breeze, if I recall correctly. I don't mean "lol it shud alwys be ez scrub" but rather it was pretty much handed to you on the first attempt.