Quote Originally Posted by Fursphere View Post
It doesn't work that way. The healerS need to be dedicated to healing the entire raid, not just a specific set of characters. And be able to adapt on the fly without worrying about "other toons".
Merc, myself and 2 others have successfully done a great deal of the Naxx 25 content, inluding the 4 horsemen (that was fun...) without having anyone dedicated to healing (other than the healers in the boxer teams).

It's definitely doable.