Of course, having a fundamental understanding of the encounters in their originally designed form, and having a raid force which operates through each boss fight like clockwork, both help. While even the sloppiest PuG is steamrolling content now, you're still going to need people in the raid who know how things like Vashj's cores, Kael's weapons and Archimonde's tears work. Which brings us neatly on to how Black Temple and Sunwell have fared since the patch...
Not exactly the serious raider's favourite instance (due to overfarming, mostly), Black Temple is now a lot shorter and -- hopefully -- this'll sweeten it a bit if you have enough enthusiasm to keep farming it before WotLK. The complexity of pretty much every encounter is trivialised with the changes, although that's not to say you can be entirely complacent.
Naj'entus will (probably) still involve a spine throw, and you'll still have to avoid volcanoes on Supremus (as if you did in the first place!). Teron is trivial and most likely killable even if nobody in the raid can do ghosts. Most of the delicate beauty of Bloodboil co-ordination can be thrown out of the window, and the Reliquary of Souls doesn't live long enough to be a threat. Mother Shahraz's strict shadow resistance requirement can be written off, and while the Illidari Council can still be a tricky pull, the length of the fight -- one of its main challenges -- is drastically reduced. Illidan himself will die without a demon phase for most experienced groups, and can be tanked by a druid now, but you'll still probably want two flame tanks for safety.
One of the common themes with all these fights is that the reduced duration means there's a lot less chance for individual mistakes, such as poor reactions to Shahraz's ports, or poor performance at ghosts. Even if you are one of the unlucky few picked by the RNG, you'll probably still pull it off (or your raid will triumph anyway). If you've been struggling with one of these fights because of too many mistakes cascading into a wipe, it's definitely worth going back and seeing if you can kill it now -- you probably will. Sunwell Plateau
The design of the Sunwell marked a change in direction from Black Temple, ensuring a greater deal of individual responsibility for the raid's welfare -- i.e. if you screwed up in Black Temple only you died, but if you screw up in Sunwell you can wipe the whole raid. As with Black Temple, this is diminished with the changes, but we'd still recommend knowing the fights to some extent before running in and planning to one-shot everything with a PuG.
Kalecgos' portals are still fairly crucial to the encounter; you'll want to make sure your tanks, healers and DPS take portals in mixed groups, though you can change the strategy somewhat. The dragon's health drops fairly fast due to the sheer number of people upstairs at the start, and you need to ensure the demon actually dies in time, so you could assign your best DPSers to go down first regardless of who got ported. It's up to you how you handle it, your old strategy will work just fine, as long as you don't get entirely complacent and forget that tanks in the shadow realm need healing (or similar).
Brutallus still needs to be taunted and the raid needs to not spread Burn, but his health and your DPS means the fight is over so fast it isn't a major problem if people die. Expect to set some juicy new DPS records.
Felmyst seems to be universally dying before her second air phase, and again, is easily killable now if a few people fail to move out of breaths, encapsulates or green beams. Ideally your raid is well experienced at avoiding these fatal spells, and it's almost unfortunate that you can't really assess trialists' performance in this dimension with the fight in its current state. You'll still want to follow the same basic strategy as you did before, to ensure mass dispelling, but as every class can theoretically AoE tank now your protection paladin can finally get a night off.
The Eredar Twins
encounter is one where complacency is definitely deadly; there are fewer Conflagrates cast, but that doesn't mean you can blow up the raid! If you don't wipe to conflagrates or the ledge boss, they'll be dead before you can blink.
It's a real shame to see M'uru
reduced to a much easier fight; zerging M'uru himself means the blood elf adds can be off-tanked (by one or two tanks, your preference) and the resulting short phase 1 duration allows for one tank to do both sentinels and spawns. Your own version of this might differ, of course, but any way you try to put it, the fight's definitely simplified now. Even if half the raid is unaware of the actual specifics of the encounter, you'll likely still beat it.
And now Kil'jaeden. This is a fight with many complex aspects, and we'd recommend familiarising yourselves with the original version of the encounter
before attempting the 3.0.2 version. The change to KJ -- reduced health -- has a lot of knock-on effects, reducing the duration of each phase and thus removing a lot of the danger of the encounter, but there are still basic steps from the original strategy you'll want to take.
For example, although you'll find he only casts Darkness of a Thousand Souls
a handful of times -- depending on how fast you kill him -- you still need to know what to do when he does cast it. Meteors will still land, and you'll have to avoid them. The raid still needs to spread out to avoid excessive damage from Fire Bloom and Flame Dart. You will find that the most hectic part of the fight, phase 5, is a lot simpler when it's over so much quicker; also, you can tolerate a lot more personal error than before, so even if a couple of people die to meteors it won't be the end of the world.
As with the other fights in Sunwell, it should be pretty easy to take someone new along and tell them "stand here, when you see a hellfire animation on the ground move there, when you see him casting Darkness move here" without explaining much of the actual fight's mechanics to them. It'd be a shame, of course, to deny people the joy of understanding such a complex encounter, but raiding post-3.0.2 isn't about complexity; it's about zerging content as fast as possible, for levelling gear or simply for the fun of finally having completed endgame.
We'd love to hear more about your post-3.0.2 raiding experiences, so feel free to chip in below! Best of luck to anyone trying these bosses for the first time -- judging by the number of new kills recently, they shouldn't be too difficult for anyone.