The set I made. A comfortable 16k spirit with potential for more if needed and 8.6k mastery. At 14.5k spirit I've been having hardly any mana issues (1/12H, 12/12 normal). It may even end up I start reforging out of spirit with the way it's going. Other healers in my guild are saying they only want to be at 14k spirit. I think people here may be way overestimating how much spirit you want.