Given the chain heal seeks out the lowest HP person in teh group it seems perfect. By getting restro shaman I should be able to heal "good enough". I can still get one priest for rez and one tank. Taht will give me 18 mages. So I can do 4 groups that are 1 sham and 4 mage and the main group of tank priest sham and 2 mage. Main group can lead and tank will target for everyone, and tank can hopefully draw fire in pvp and agro in pve. And I can still go undead on the mages/priest/warrior and something else on the sham.

Keep in mind that the 25 will never be in a raid during exp times. If I can find a fast spawner or spawn area, Ill have 1 group of 5 getting the exp with everyone else ungrouped. Its just a matter of finding a fast spawn or spawning area (i.e. where they spawn instantly if killed instantly .... )