You know, if that "edge" was actually there, Holy Priests would be completely dominating on Heroic Stone Guardians. You have 20-25k Spirit in there for majority of fighting, allowing you to go crazy with heals - same as everyone else. There's also a lot of AOE damage from Jade spamming his silly move plus a ton of tank damage. So you can even choose, tank healing or raid healing.
We won't be getting that amount of regen in normal gear, even in further tiers, so it's about as "spammy" as it can be. And yet, it's still Monks completely dominating AOE healing and Priests... well, there are few of them in rankings, but it's hardly anything impressive. Certainly nothing that makes me think "if only I had such regen normally, I'd pull insane numbers and easily outheal everyone".