The marching orders have been given. With the green lighting of dual specs in the upcoming 3.1 patch, Priests of any discipline will be faced with an enormous decision that dwarfs the question of going Holy or Shadow (and Disc)!
First, a brief history lesson.
For the longest time, the healers struggled with questing. Soloing and doing dailies was a monumental effort due to the of our spec to Smite those that would oppose us! In Burning Crusade, our offensive spellpower was raised to so that it became a fraction of our healing spellpower. In Wrath of the Lich King, these become consolidated into one overall stat.