So when the level 60 Druid Tank & Priest leave the raid do you quickly convert the existing raid with the remaining 5 players back to a party before starting DPS to tag all the mobs?

When you do that do you start a 1 minute timer and the mobs just keep ineffectually hitting the level 60 tank while your other characters AoE them down?

If you already have enough healers at cap would this be an effective way to level 5 DPS (Warlocks &/or Mages)?