As someone who healed some raiding content (pre-wrath, still working on gear for wrath) I can just advise you to do two different classes. It hurts a raid to not have poison removal. Also, it is a waste to have two of the same healer class giving out the same raid buffs. Each healing class has its own strengths. Having two healers of the same class often stressed out our raids a bit.

As to the whole Circle of Healing CD update, it's a non-issue for Discipline Priests
"I was discipline before it was cool." - Myself in guild vent last week.