I'm personally not a huge fan of Perseverence, to be honest. It's much less then 6% reduction, and most damage in Firelands is either designed to kill you because you stepped in something really bad, or it's massive raid damage which you will be receiving massive raid healing. The innate magic damage reduction from Moonkin form will prevent you from being the first dead. If you die due to too much damage, half the raid will have been dead before you and it was a healing issue. I have never picked up Persevrence and never die early to things unless I totally boned something up and had an instant kill type of situation. BotG may be a minimal dps increase, but it's still a dps increase.