I have read Howtopriest guide and im not sure why they tell disc to go crit after mastery. Most of your healing will come from Pw:s (60%+) then you have EAA PoH wich is already 100% crit. Then the only reason you would go crit is for your other spells wich honestly don´t do that much healing. From what i hear and maths Multi and haste work better with Pw:s then crit.
Look here:
http://www.mmo-champion.com/threads/...8#post32073818
http://www.mmo-champion.com/threads/...6#post32075236
+ Other threads on this forum that has hade huge discussion about these stat prio.
Maybe Howtopriest only looks at stat weights numbers, idk.