Now that I'm confident enough that it works, here is my spec suggestion (I mentioned it in the pve spec discussion but that thread is too unfocused):31/0/40 Shadow Mastery+Shadow and Flame
This is basically a shadow bolt-centered spec. Keep 3-4 DoTs up, spam Shadow Bolt as filler, use Imp as the pet.
- the hardest-hitting Shadow Bolts you can get now (SM+SnF);
- both hit and range talents;
- both aggro reduction talents (not an issue now, but it may well be in future raids);
- less reliant on pet DPS than Demo or deep Destro specs;
- scales very well with crit and haste;
- stronger dots than Demo or deep Destro specs.
- weaker DoTs than deep Affliction specs;
- weaker pet;
- some non-optimal points (you can't really avoid Improved Drain Soul, and the point I put in Shadowburn can go anywhere else, really);
- while Shadow Embrace is bugged, the points in it are worthless, since you should let an Affliction warlock get SE for it'll benefit him/her much more than it'll benefit you.
The Shadow Embrace problem actually suggests that while the bug persists, you should really change the affliction part of the spec and get some less-than-ideal talents which will, at least, be better than wasting 5 points in SE. So the current, non-ideal version of this spec would probably look something like this:30+1/0+1/40+1 shadow spec
Soul Siphon is obviously useless for raids, but it's still useful for soloing. The last point can go to a lot of places: Eradication, Dark Pact, Shadowfury, Empowered Imp or Improved Imp.
Glyphs should be Shadow Bolt, Imp and then you choose between Immolate/Siphon Life/Curse of Agony/Corruption, depending on your personal preference.
What I like about this spec is mainly its simplicity. Keep 4 DoTs up (or 3 if you end up casting CoE/CoR), set your imp loose and spam shadow bolts. Since your imp isn't a big part of your DPS, in fights where it'd be tough to keep it up you can just keep it phased and still do decent DPS.
Right now it obviously doesn't perform as well as deep Affliction or even deep Demo. But I suspect that we're currently living in a situation very similar to the beginning of BC, when lots of warlock specs were competitive - but as new content and gear came out, it was clear that shadow bolt scaled much better than either DoTs or pets, and then Destruction easily came out on top. Of course, Blizzard seems to be aware of the issue and apparently fixed a lot of the scaling issues (especially with DoTs, but not so much with pets), but I still think that Destruction will eventually scale better. And if the choice is going deep Destruction with annoying rotations and talents (I really hate Fire and Brimstone), or a demo/destro hybrid that emphasizes your imp (which still can easily die and won't scale as well as your own spells) or this build I'm suggesting, the latter may come out on top (or near it, at least).
This is the 25-man Patch WWS
I have, using an inferior version of the spec I'm proposing (still wasting Shadow Embrace, and with points in Soul Leech), on a non-optimal raid (no moonkin, ele shaman or demonic pact) and with a non-optimal player (me, still mostly in Sunwell gear and playing with 500ms latency). And yet it still didn't lag too much behind the affliction warlock.
I think this spec holds promise, and it would be good to get more feedback from better-geared and/or less laggy players. Comments? Criticisms? Suggestions?