Let's for a moment forget that Survival Hunters are in the equation. We do this for our sanity. For now, let's focus on getting our own performance up to par. The spec I use for raids is a 53/ 0/ 18 as opposed to the more popular 56/ 0/ 15, but I've found it gives tremendous returns with just a few talent points allocated in some talents. It's been difficult, but it's slowly becoming rewarding. I say slowly because it must be noted that some classes scale better and faster with gear and the raid. Let's take a quick look at the build right after the jump.
Everything about this build is pretty standard, although a few things might stand out as being peculiar. The first notable thing is that we invest only one point in Eradication. This is because two more points for a mere percentage increase (you get the same amount of haste when it procs) devalues the talent points, so they give more bang for the buck elsewhere. In this case, one point in Molten Core, using the same principle. Even at 5%, the buff will almost always be up considering the number of DoTs we'll have on a target. Other than that, it's a couple of points thrown into Cataclysm to help push Immolate's hit up to par with other Affliction spells, which benefit from Suppression.
This is the one thing that has made a lot of Warlocks shy away from Affliction as the cycle for 0/ 41/ 30 has fewer spells to cast and doesn't require as much maintenance. That build also gives good returns as it's not as gear-dependent. In Affliction, the only important sequence is the initial volley of spells, and should be on a priority basis thereafter. It should be Shadow Bolt followed by Haunt to apply two stacks of Shadow Embrace, followed by Unstable Affliction and Immolate. Both spells have a 15 second duration, so should always be cast in tandem to help ease the rotation a little bit.
The rest are the instant cast spells, Corruption, Curse of Agony, and Siphon Life. Alternately, you can cast Curse of the Elements as you have Malediction, and should ease your rotation considerably. After this initial cast, it's a matter of DoT uptime which can be... hellish. Shadow Bolts are there for when everything else is on cooldown.
Sadly, no demon will give significant DPS returns on this fight except for the newly improved Doomguard and, if you can time it right, an Infernal. Felhunters, despite their Shadow Bite ability which is supposed to scale with DoTs, barely does more damage than a run-of-the-mill, untalented Imp. In many cases, having an Imp out is even better because it stays at long range and can have Phase Shift toggled for survivability. Even with the newly buffed demon health, Felhunters tend to die a lot. At any rate, these pets will deal anywhere from 150-200 DPS on average, perhaps more if they scaled better with the raid (which they don't).
On special fights, pure DPS races, such as Patchwerk, use a Doomguard. The new situational demons have been greatly improved and it seriously makes me wish I could keep the big guy around indefinitely. Doomguards deal significantly higher DPS than any pet available to Affliction and should be used whenever you can manage it. The only caveat is that, obviously, it is impossible to do this through Curse of Doom as no trash mob lasts for a minute and even then you'll need to land the killing blow. Good luck with that in a raid. Your only real choice is to use the Ritual of Doom, which sadly has a 1-hour cooldown and will set you back 1 Gold for a Demonic Figurine.
Keeping all DoTs up is simply the most difficult part of playing an Affliction Warlock and is arguably the hardest playstyle in the game. Harder even than the flavor-of-the-month Trap Dance of Survival Hunters. The difficulty isn't just in keeping DoTs up, it's in not clipping them. It's easy enough to keep mashing the buttons so all DoTs are always on the target, but this will often result in clipping, or overwriting the DoT. Whatever happens, do not ever, ever clip your DoT. While it might not seem like much, this is actually a significant drop in DPS.
The best way is to start casting spells when the DoT is about to expire so that it lands exactly as the previous spell has expired. Naturally, this isn't easy at all. You can watch your timers manually using the default UI, although I prefer to use Ashelya's DoTimer with some OmniCC thrown in for good measure because I'm just not that hardcore.
It's important to note that Haunt is not a DoT which means you can reapply it even though the Haunt debuff still has some time on the target. This means you should cast Haunt every time it's up, taking priority over other debuffs, even if they expire at the same time. Haunt also has a slow travel time, so this should factor into your calculations when refreshing Corruption.
Ironically, the best glyph for Affliction is for a Destruction spell, the Glyph of Immolate, followed by Glyph of Siphon Life. The last glyph slot is up for debate, although it's notable that the Glyph of Curse of Agony helps simplify our rotations. It's not a straight up DPS increase, so I actually prefer Glyph of Corruption, which stacks with Nightfall.
Gear will factor highly into our DPS, mostly because our abilities can only scale so much on their own. This makes the set bonuses of Tier 7/7.5 important, even if sometimes an individual piece gives better statistics than a set piece. I like the spirit bonus because it balances out Life Tap, which is often a dip in our DPS. In fact, the bonus rewards mobility fights which is when we can Life Tap with little penalty.
Procs from items such as Dying Curse (Heroic Naxxramas) and Illustration of the Dragon Soul (Heroic Obsidian Sanctum) are tremendous boosts to DPS, which make them highly desirable items sometimes even over Tier 7. The point is that it's not going to be a cakewalk. It takes tremendous attention to detail as well as a serious commitment to gear upgrades in order to deliver. It can be frustrating, certainly, but once you reach a certain gear threshold and get those rotations down pat, you'll find that your raid DPS will boost up considerably. Maybe even catch up to that new Survival Hunter with a blue gun.