My experiences thus far with this fight is it's a pure dps battle. steady and calm is important, but if you aren't getting reasonable dps on him, your healers will start to get overwhelmed. Warrior and Feral tanks should be in full dps gear, paladin tanks are a bit tougher - we've been having them help with healing. Minimum 6 of your 10 should be going all out dps, ideally 7 of 10. Keeping everyone alive is paramount to success, even losing one dps or healer, especially early can be enough to lower your aggregate dmg/mitigation to where you can't drop him. Making sure people don't move during the flame wreath is the first step though. Once you get that down (which really shouldn't be *that* hard), the rest is a dps/endurance fight.
One time we downed him was crazy, it got down to the wire when we got him to around 15% we started losing people. I died 3 times that fight being battle rezzed twice, at the end I was weaving in moonfire's between my heals trying to squeeze out the last few percentage. Our healing pally was the last one standing and got a last moment lay on hands, hammer and holy shock in and dropped the shade - OOM and with like 2k hp left, everyone else was dead. It was nuts XD.