I say go for it. If you almost had it with elementals tanking, and needed more healing, a geared holy priest should work well. I have a pally as my main, so i'm going the tanking route. Worst case is it wont work, and it will motivate you to gear out the pally. Heck, then you'd have the holy trinity, and could try heroics the way blizz designed them to be run (not that there's anything wrong with 5x dpsing) Unless of course the pally and priest share an account. You could always xfer...