Soooo just did this on 8 man nightmare... It's a joke compared what 16 man once was. No enrage, only 1 double destruction each phase. Only difference between HM and NiM was the exploding mob which isn't even a problem!
On another topic, 16 man after nerf. What are differences?
Only one. When you push into the last 5% of the health pools there used to be an enrage....now there is not.