Quote Originally Posted by RainDurell View Post
Bringing a BLM over RDM/SMN wont break the party, it just means you wont have battle res, and instead you get higher dps.
Black mage brings considerably higher dps than Red Mage. on Summoner, they about par once your factor in Summoner's Devotion.

Red Mages in heavy PDPS set ups are generally only about 5-7% behind Black Mages when taking into account total damage contribution.

Generally speaking, in terms of total Raid DPS, this means that if the raid with black Mage is at 100%, then the raid with Red Mage is around 98% and the raid with Summoner at 99-100%