I have a 70 shadow priest on the same account as the pally that i plan on swapping out at 70. I wanted to to have 5 shadow priests it pvp at 70. I added the pally in there to have a tank and beacuse there is no point in having 2 priests on the same account. if it works out later than healing agro and dpsing is too much agro then it's not going to be a problem to make one holy. But i think 3/3 shadow affinity and salvation should be enough to keep any agro off my priests. Healing is relitive to what your tank can mitigate. The good thing about having a central figure like a pally tanks is I can twink the pally out with enchants and felsteal shield spikes and the best gear i can get for him like you would do a normal twink but the priests are support classes so they don't need that much juice. with 4 VT's going, mana will never be a problem, neither will the mana cost of popping in and out of shadow form as needed. If i have to i can start a fight in normal form and let the pally get some aggro from concecrate while tossing out concecrate and crusader judgements with ret aura up and just heal him with renews or flash heals. once he has a lot of agro then i cna pop over tho shadow from and toss up VT VE and SWP and go back and renew. The healing is spread out between 4 priests so i don't see how it would draw anywhere near the agro that 1 holy priest would creeate. not to mention SW with 4 PoM's bouncing around. The more i think about it i can't find a bad point in 4 priests other than no cc but cc is just a hinderance to a pally tank. I play a feral druid as my main and i've tanked up to bloodboil in BT and Archimond in Hyjal. I've ran Heroic SH many times to key people up for the Eye, But I was amazed when i went in with a pally tank on my shadow priest and it was an absolute joke how easy it was.