I play 5x 60 twinked priests and yes, it is very hard on the mana. But i glyphed dispersion so i can spam it every 1.25 mins for mana regen (yea, i use dispersion for the mana rather than the dmg escape lol). I use holy nova for healing and self bubbling.

Go human team. I'm 5x nelfs and I recommend humans for the trinket racial. It's very nice and i miss it greatly. That and the spirit racial increases your dps.