Well, when phrasing it like that, you basically described every encounter going from N -> HC (more dmg in, need more dmg out, new strat/technique) :PYeah, I know. But looking at videos and tactics, they don't seem to be that much more different from normal mode except for tighter dps requirements, higher damage of mobs and somewhat different order of add handling.
Basically, the boss is active from the start, the small adds hit like trucks, the fonts will damn near 1-shot non-tanks (and still dent tanks pretty hard), rings need to be soaked by a non-tank or the tank dies, swaps/brez CAN put you through the rings (lol z-axis) and get you killed, the matter swap will just about 1-shot anyone if not handled well, and so on. I'm not saying that it's the hardest fight in there, it's certainly much easier now with all of the gear, but there is just a lot of personal responsibility and add/debuff/real estate management to go on for the fight. Adding in 9/24 other people (and the space that they take up) is the real challenge. I promise it's harder than it looks in videos haha.