Even if the heal was an instant cast, complete heal, but on a 2 minute cooldown.. that's not very effective.
Chances are it will be 2-3 Death Coils, or even 4, for a full heal... which is dependent on having Runic Power.

My DK's had glyphed Rune Tap.
Which used to be a 50% group heal, every minute.
Techincally, if I ran them as Blood x5, I could still have this.

In addition to that, they had the passive healing from being in Blood Presence.

They feel rather squishy at the moment (5x Unholy DK's).
I really like Unholy, but Frost is looking nice with Howling Blast.

Either way (Unholy/Frost), I don't get Rune Tap.
I have bandages and endless healing potions.
And a mapped key, to round-robin Taunt.

They won't have Lichborne until 81st, and are likely to stop at 75th for their alchemy contribution during Cataclysm.
Even with Lichborne, it's another small healing tool.