Reckoning is a must for AE grinding. I picked it up from the beginning, and love it. I'm currently 55 in western plaguelands. I pull 8-12 lvl 50-52 mobs, put up Seal of Light, keep up Holy Shield, and never drop below 3000 hp. You just can't beat killing a dozen mobs at once, getting the same exp you would for completing a quest lol.