I guess it's all in how you do it, but I'm an affliction lock with a wow-heroes GS of 2643 (for reasons I'm not going to get into here, I hate the GS addon and refuse to use it). On heroic bosses, I pull about 4.5k dps, in raids (depending on buffs) I usually average 5k due to all the bonuses I get when the target is below 35%.
I'm saying all this because I think Affliction is the better spec. I don't concern myself with all the theory crafting and all that, but I know what is *fun*. It's not very fun to have a rotation that consists of 4 spells (I was Destro for months before I changed to Affliction).
I'd definitely give Affliction a shot if I were you, it's way more fun. If you choose to, the rotation I use is:
Haunt > Unstable Affliction > Corruption > Curse of Agony > Spam Shadowbolt > Haunt > Shadowbolt > Unstable Affliction > SB > Drain Soul (when below 35%... 25% is preferred to start, but take what you can get, it's still a dps increase at 35%)
I don't know what the name of my talent build is or if it is even a standard talent build, but I like it and it works for me. Considering my GS, my dps is pretty good. A destro lock in my guild actually has a GS 200 points (again, wow-heroes) higher than mine, and I out-dps him.
You wouldn't need to change gems or enchantments; priorities are still Hit > Spellpower > Haste > Critical Strike. It's been a while since I was destro, but I'm pretty sure that's the same priority.
really, DPS is king at the end of the day, *if you survive it. To me, gear scores are mostly akin to having a certificate proving you're mentally stable and sane. i.e. it's the kind of thing you assume is going to make people wonder when you were not sane, and just how long ago that was. i find the new beta version of GS is also unhelpful with the gear evaluation, since it's lazy about stat bonuses, the GS raid/party tooltips will recommend tanking/ap gear as an upgrade for cloth, etc. plus it cuts about 20FPS if you're in a raid group.
something like elitist group is cleaner and easier to make snap judgements on gear if you PUG a lot, but it doesn't suggest or rate loot as upgrades, etc.
let's see, gear, gems, glyphs, chants, i'd leave to EJ/wow-heroes.
be.imba.hu has a few better enchant/gem recommendations IME, but it also has pie charts, which is nice, and looks better.
to some extent, everyone's in a similar boat with curses, COE is sweet, but having to switch to COA/corr if you have an unholy dk in the group gets annoying sometimes, in '10man' , unholy DK's will be out there, i.e. our guild has ~8 unholy DKs in the top 50 on wow heroes, so its hard to not have one just lying around according to simcraft, and EJ, CoD ->COE-> COA, but, IME, CoE makes a good marker to see if you've put SoC on a mob, so you can come back and burn down as normal, since it also increases SoC 's radial burst of damage on the target, it's handy to 'dot and nuke' and sail through heroics.
i dislike CoD on principle, since it's only good on boss fights, and normal rotations, its much, much too easy to forget to recast CoD, hilarious also is the ultra rare doomguard spawn that takes out the healer by accident after the boss dies (was hilarious in naxx when this happened), so it's got that bonus if you do use it.
for 'DPS alone, AOE is where the big numbers happen, switching to SoC instead of RoF will push you above 5k DPS in heroics, and in general SoC is much, much more efficient, if mana draining. destro gets a big boost out of SoC as well, it often hits for 4k+ instead of 3k for RoF, and it can be placed on multiple mobs, ideally ones with ~40k health left so you can DL/RoF the survivors.
the downside to soc is threat spikes, you will have to switch targets often, to avoid crit spikes pulling threat off tanks doing 6k DPS compared to 11k crits. For destro locks, the skull/triangle/cross will be merely suggestions, unless you can pull off 4 successive SoC's on different mobs and then start up a rotation on the skull, without hitting 90% threat, you will likely have to switch targets when you start to peak threat on one mob, and just single-target burn/switch/burn/switch, etc, until you can Drain Soul or cor/coa/immo/cb/conflag/drain if it's a tougher than usual boss
as for afflic, it's more juggling/memory games if you switch targets, since you need to see more timers. raiding with affliction, is tough. a 10man s almost entirely 'rotation-> fire -> rotation -> fire -> adds -> fire +adds-> rotation-> boss explodes, you now have 30% health + 40% mana-> rotation-> fire + adds-> haunt falls off boss-> adds, 5% mana remaining -> fire -> rotation -> bloodlust pops, you have 20% mana left and the healers have still forgotten to heal you, etc.
while nearly the same stuff happens in destro, you will have killed most of the adds earlier instead of having to switch to refresh haunt on the boss while on the move. if you're used to the timer/rotations, you can refresh on the fly, most people miss a few haunts in 10man due to being given 'range' duty with the hunters and mages who have burst/cc, you might have CoW which lasts about 5 seconds if it lands, sic, etc.. in short, there's fun to be had, if you want to find it, but afflicion gets tough.
in 10mans, you will also have to get used to hovering over SShatter and walking right up to the boss in some cases for the 40yd range to work, it's about the same as DCircle, i.e. ugly and akward. you should also get familiar with clipping incin's which produces your highest consistent burst DPS by using the quartz cast bar to learn when to 'cast' in the red zone (casting on the GCD instead of waiting for casting /flight time) of each spell, you can bump 3500 to 4300 dps in some cases just watching the quartz bar.
as for gear, everything looks fine, i'd aim to get the t10 gloves with 60 EoF's for the 2t10 bonus asap, but it looks nice otherwise. perhaps the moonshroud/bejewelled bracers if you have a tailor in your guild, since you can get the ~200g gems for 10k honor (run WinterGrasp for easy 25k) off the org vendors, and the mats are pretty cheap for bejewelled/moonshroud, compared to equiv. 245 gear off the AH or from heroics/EoT gear.
in simcraft, i loaded your spec, which comes up as 5200 DPS raid buffed.
it's merely suggestive of a scenario/spec/gear/buff combo, i expect unbuffed DPS to be around 4000 dps or so, which isn't bad for heroics, the rest of the inflated DPS typically comes from crit as well as optimal rotations, buffs/debuffs, etc.
as for spirit/regen, half of your mana comes from LT, which is OK, but only 20% comes from replenish, which is going to mean frequent mana issues, if you can aim for more spirit gear, it will help with mana and spellpower and general mana/hp recovery with fel armor.
as for gear scale factors, without the t9/t10 bonuses, you have the following scale factors for new gear:
scale factors are a bit confusing, but they are used to estimate gear upgrades for your spec. if you add or remove a set bonus, you will have to redo simcraft to get new scale factors, otherwise keep those until you figure out simcraft. scale factors are used to rank gear and DPS, but it is entirely dependent on your current stats, your talents and glyphs, set bonuses and the spells and buffs you use as well. by seeing how much higher your DPS would be with +200 extra int, haste, etc. etc. you can 'weight' a particular stat compared to another stat.
if you use those numbers in wowhead or lootrank, this will give you a way to rank optimal gear for upgrading. if you get RhadaTip , enter in these custom scale factors, it will give you a consistent estimate to your DPS in game, and when looking at gear tooltips in tradechat, AH, loot / atlasloot pages, it will put your current DPS/new DPS in the tooltip, and also the DPS for your offspec. this "shows" what gear will actually be an upgrade, and by how much in terms of *your* DPS values.
it's a nice addon + app combo if you use simcraft, else, use wowhead/lootrank and make a BIS list. if you use lootrank, it will create a top-50 upgrades using your armory page to read what you have currently, and suggest best in slot for you.
the other thing simcraft is good for is DPET, it's misleading since it shows roughly how much damage it does over the whole casting/effect period, DPET on a DoT which can crit will be 9-10K or more, where the DPS will likely be only 500-700. as far as DPET goes, with raid buffs applied, you get ~3500 spell power, which gives you a 9.7k conflag, 8k cb, 7k immo, 6.6k cod, 6k incin, 4.5k coa, and .8k firebolt
as far as a DPS breakdown, about 40% of your DPS will come from incinerate with ~2k dps, 11% comes from the imp with 600 dps, 20% from conflag at 1k dps , and 600/700 dps from immo/Cbolt, with CoD only doing about 150dps . while this seems small in contrast, it's over the whole boss encounter and cooldowns limit things for a reason, i.e. bliz has no soul for unrestrained mayhem.
for your off spec, you don't have quick decay which boosts corruption with haste, and you've got the succ glyph, so it's 4.4k raid buffed with your current spec, with quick decay and the 'improved' felhunter, it's 4.9k DPS.
without QD, you'd have 1.2k dps from corruption, but 560 dps from succ (glyph'd) with QD, you'd have 1.8k dps from corruption, about 35% of your total DPS, with 700 dps from UA, 550 dps from FelHunter, 930 from Sbolt, 350 from haunt, 550 from Dsoul and the int/sp boost to stats
your off-spec scale factors (with the QD glyph) would be
for affliction, if you got the nevermelting ice crystal trinket off PoS, it would stay up with corruption for the 20% boost to crit, instead of falling off, which is an extra bit of DPS. haste would also help, so black magic instead of +63 spwr on the main hand would help a bit too, the 2t10/4t10 would also inflate dps for affliction/destro as well, so it's not all bad.