Oddly enough, our run through Heroic Slave Pens reminded me of the first time I ever ran regular Slave Pens. The only difference was in the magnitude.. but it felt the same.
The first time I ran Slave Pens I was level ~64 and ran it as the healer (while still spec’d protection). It was hard to heal through (especially since the tank we’d picked up sucked). I think the only real difference was on Heroic I never ran out of mana.. but I did have to chain cast heals quite a lot. Oh.. and our tank didn’t suck 
We were: Gongniu (Warrior Tank), Tatia (Paladin Healer), Flashback (Mage), Raouen (MM Hunter), Fynriss (BM Hunter).
The last boss dropped [Breastplate of Righteous Fury]. The group let me have it (since I was the only plate wearer in the group and because they were all focused on the Primal Nether).
[Breastplate of Righteous Fury] is on my Healing armor list. But now that I look at it, I’m not sure if it’s an upgrade.
I’m currently wearing [Breastplate of Many Graces]. If I changed to the new one I’d see the following changes:
+29 Armor
+21 Strength
-11 Stamina
+ 2xred, 1xblue socket (socket bonus: 2 mp5)
-11 mp5
-39 healing
+2 spell
Even with all those gem sockets, it’s just not looking like an upgrade. Even for my +spell set. Hrm.
It looks like for my chest piece, without going into 20 man raids, my path to upgrade are:
[Breastplate of the Lightbinder] – Terestian Illhoof @ Karazhan – +26 healing +2 mp5 +12 Int -12 sta
OR
[Chestguard of Hidden Purpose] – Akil’zon 6% @ Zul’Aman – +24 healing +4 mp5 +3 int -7 sta +3 sockets
So I guess I’m stuck here for a while.
Many Graces is the best blue healing chest, imo. Righteous Fury is more a Retribution chestpiece than anything else.
If you’re just doing 5-mans and heroics, there are 2 unofficial “sets”: Red Lawbringer, for Retribution; and Purple Judgement, for healing. Purple Judgement is pretty much the best healing gear you can get before raids.
or it’s for tanking