IMO it's nice to have one of your standard tank healers to be a disc priest... it's not necessary but I think diversity is a strength for your raid rather than just choosing to use 2-3 holy paladins. Of course Holy Priests can do the job but the disc tree is built to handle single target HPS and will do a more effecient job.Originally Posted by heerobya
Some benefits for disc
1. They can prevent damage, so in fights like Loatheb their form of healing isn't totally negated.
2. Penance is probably the best healing spell in the game, it deals with damage spikes incredibly well to provide safer healing.
3. Can bring DS to your raid and while that will be available to all priests in 3.1 they will have acces to Imp DS
4. Pain Suppresion is another 'oh shit' button your raid can utilise in whatever way they wish, and it's mechanic is different and more desirable in certain situations than GS
5. Due to their heavy crit setup and many fast casting heal style they will almost certianly have inspiration up on the tank giving them 25% more armor. Something holy can do but not nearly as well.
So if you are asking can a raid function without a disc priest, yes they can with 0 problems but if you're thinking about trying to make your raid more diverse and better handle a wide range of encounters/situations I think having 1 of your priests as disc is a good idea.