Here's a fun strat my guild uses.
EVERYONE starts on live side at the beginning of the encounter. Around phase 8, the gates open up and all the dead side mobs start to funnel in. In 25 man, we use our Warrior (me) to tank the live adds and put a DK and Pally to handle the incoming mobs from the dead side.
They can drop DnD and Consecrate to gather the incoming adds, and we have ranged AOE them almost immediately. The DK and Pally will also need to pay specific attention to mobs that may make it through and taunt them back as soon as possible.
This certainly isn't the safest method as it adds some chaos (and usually some lag), but it is a whole lot of fun Also beneficial because ranged can stand in the middle and dps Gothik no matter which side he ports to.
We've done this pretty successfully on 10 and 25 man. This would have been a great achievement for Blizz to add