I have actually had decent experience powerleveling 4 toons with a 70 priest. I can clear the Armory in 15 minutes. Priest is in blues and greens only and I had to respec her for holy nova powerleveling... lol. But she does well. Self-shield, run around pulling large amount of mobs, holy nova. I have to drink before repeating. I do the Armory in 5 pulls and one boss stop. Since holy nova generates no argo I have to park the kids out of line of sight and do the AEing close by.

I tried 70 warlock and 70 warrior both with better gear and found that while the pace was faster I really apprieciated being able to rez if I accidently got one of them killed.

In the 50's I may have to abondon the priest or atleast add another 70 and drop a lowbie to level later as only 3 of the 4 are priority.