I've just finished running through ZG (47/48 now). Started at 43 to get a feel, by 46 it was straight forward.
The advice I can offer is practice, Holy Shield and kill the casters first.

With your grounding totems down, the casters won't be able to do any damage before you've killed em. Meanwhile your Pala is keeping the others entertained and building a lot of aggro. Holy Shield is awesome for that, with prolly about 1k threat on the targets by the time you've nuked a caster.

The mobs to watch out for which could potentially be doing you the most damage are the ?blooddrinkers. When they are close to your pack they do some health stealing (I need to look up what it is!), which is a pain, so just make sure you tank em away. Having your mobs on follow all the time could make this tricky, so have them set up a position with their totems before you pull.