From what I can tell, if I took my current gear and stacked spirit I could get to about 15000 spirit, at the cost of around 9% mastery, 4% crit, and 3000 spell power. This would put me at around 18000/5 mana regen, and we'll round up just for the hell of it and say 20,000/5 regen. Over the course of a 3 minute fight, this is going to equate to ~145,000 mana. If I were to put this in terms of how many spells I would be gaining for free per fight it would be basically 8 flash heals, or ~11 prayer of healing.
Now, let's say I don't get ANY spirit from my gear period, which is almost impossible, but say I only have 6000/5 mana regen. That means over the course of a 3 min fight I would only regen ~15,000 mana which is almost 1 flash heal.
The question I'm asking myself, is 7 flash heals worth losing so much throughput? When we consider that the harder a spell hits, the more efficient it becomes, and theoretically the less spells you have to cast.
Someone please help me see the light?