I don't usually mention my alt except in her support role to my hunter. But last night after our 25man raid, I broke off and did a heroic daily with my hunter and then my alt. My alt is a shaman healer.
So it was me and a top DK DPS from my guild in the LFG. We got a modestly geared tank and some other measly DPS. From the moment of zoning in. I was barely able to keep in range of him to let the heals fly. We were out of combat maybe four times the entire run.
We finished Heroic Halls of Lightning in about 9 minutes. Maybe 8. I wish I was keeping track. There were a couple times two or more people were under 20% health. The worst of it was up front when the tank took two packs on the first lightning boss when the mobs were empowered and when I had the lightning DoT/debuff that nukes you if you move. I was of course far out of range of the tank and my DK.
I'm proud to say, nobody died and I didn't even need to pop a manatide totem. I think we might have been able to shave off a minute or so if we had two more top DPS. I've just never seen pulls like that before.