For the record, even with the nerf H Ultraxion requires you to have 36k as an average DPS for all your DPS, this assumes that you 2 heal it and have 6 DPS. This is factoring in 2 tanks doing 16K each or higher.
I want to note that if we had our regular tank on, our other DPS would not have been tanking on his poorly geared alt. So we could have replaced the Warlock only pulling 26K with a DK pulling 36K+ and that also would have given us another cooldown person to use for soaking Hour of Twilight. And the regular tank pulls 20K easy. I'm pretty confident the only reason we downed it was the fact that yes, it was nerfed, and we have two people pulling over 40k right now.
As for our progression, we've been working on (Heroic) Zonozz, Yorsahj, and Hagara for a while now, as well as Ultraxion. Who we work on has more been a product of attendance as we have a tank who is starting to flake on us, and we have 3 DPS who are flaking on us randomly.
In fact, if ever I'm talking about bosses, just assume I'm talking about heroic unless I'm talking about Spine or Madness.
Oh, speaking of that, got the achievement on Spine for rolling Deathwing around. It is a very very easy achievement.