To add to what Seldum was saying, I use Pally/3 ele shams/warlock and it's a great team. 3 shaman chain heal the group nicely, and even Ele spec they can put 3 big heals on the tank for 12-20k total in a pinch. Lock gets me the 13% magic dmg bonus as well, boosting all dps.

But... Im hitting a point in HoS/HoL where I am going to try running one sham resto for a while, since my team is only level 78 with a 4600GS tank and I've wiped pretty hard in the last couple days learning these new dungeons from the boxing prespective. I hope these wipes are just due to lack of strategy and knowledge of the fights, not from lack of heals, since I've really enjoyed not having the extra requirement of controling tank and dps and healer.

Just my 2c....