For H Chim Chim, each priest healing spec is very capable for tank healing. Whether you're healing the soak tank (Double Strike) or the Break tank (which only needs to be above 10k hp) you need to use the abilities properly. As Ashelycakes said, for Holy spec, Serenity makes this silly easy. Holy Word: Serenity is instant and heals for upwards of 10k depending on gearing, for me it's an average of 18k. Generous utilization of Serendipity (the stacking Haste talent for GH) after massacres is very helpful as well.
For a Disc priest, I would recommend healing the Break tank. Bursting up the Soak tank can just be annoying.
Possibry brings up a great point though. Priest have the best aoe heal to get ppl + 10k after massacres. So, unless you're without other options priests are more effective in a raid capacity.
Last edited by Ardoris
on March 4th, 2011, 9:07 am, edited 1 time in total.