If you have problems with people surviving outside, run 4 healers. Have two of your healers stay out to heal the raid, have two others assigned to the boss. This is of course largely reliant on the number of hybrids your group brings. Our 10 man has sufficient DPS that we drop to 1 tank, 4 DPS, and 5 healers (3 on the boss, 2 on the raid) to make the encounter as short as possible. This fight is mostly about finding the right balance between DPS and healing. The more healing you can afford to put on the boss, the better. However you can't sacrifice DPS to the point that they can't kill the adds fast enough. Also, naturally with experience your DPS will handle target switchs smoother and do their job more efficiently and as their efficiency increases they can handle more with less. Also don't be afraid to have people respec, if it gets the kill thats what matters. When you get stronger with the encounter you can likely do it without requiring respecing.
"In anything, if you want to go from just a beginner to a pro, you need a montage." /w TankSpot WTB Montage for Raiders.