That being said, you're right in that it's best to see 1 SCH and 1 WHM if two healers are needed on a tank. There's no real good reason to stack two SCH on the same recipient in a raid situation anyway.
I'm not so sure about that... with the fairies having those auras for skill speed/spell speed and healing, its certainly possible that there may be reasons to stack them.
From the skill descriptions it seems that 2xSCH could fulltime buff party skill and spell speed.
EDIT: I'd also like to mention that everyone's assessments of SCH left out the 300 Potency cure that both Fairies have and all of the other abilities they have... Edited, Aug 4th 2013 7:22pm by TenchiHawkwing
I certainly didn't leave them out. But until we know how intelligent the AI is or even how often it can cast Embrace, it's difficult to tell how useful it will be in a raid situation.
The fact of the matter is, unless the barriers stack, in a raid situation where 2 healers are needed on the main tank, WHM and SCH would be far superior. That doesn't mean you can't have 2 SCH in your raid, it just means one will be tank healing, and one will be raid healing. Think about it this way:
If 2 SCH cast Succor II, and they both hit between a boss swing, you're getting 2 300 potency heals, with 1 300 potency shield, for a total of 900 potency. (Because one shield is overwritten or even worse, has no effect.) With a Cure II and a Succor II, you're getting a 300 potency heal, 300 potency shield, and 500 potency heal, for a total of 1100 potency. A 200 potency difference may not seem like much, but that's a 20% increase. Over the course of the fight, that's going to make things a lot easier.
We're also not really even sure if certain spells can be used on raid members outside of your party. Will protect hit raid members as well as party members? I guess we'll have to wait and find out. If not, a WHM will be absolutely required in the tank PT due to proshell. Edited, Aug 4th 2013 5:40pm by RamseySylph