Went back two nights later and 3-shot Anub to complete our Mad Skill achievement. Finished with 46 attempts remaining. Was a great job by everyone to focus and bear down on this one. Really feels like the guild has gotten back and perhaps even surpassed its pre-nerf M'uru stride. Now we just need to carry the momentum forward, finish off insanity and prepare for Arthas.
PS: Looks like 21st guild in the US (51st World) to get this particular achievement. Very nice.