having onyxia or maygos turn towards you in phase 3 is often genuinely amusing when there's 2 tanks and they still can't keep threat against a destro lock. i would say it's a problem in the class,

apparently shatter, is the answer ?

switching to SoC as an opener and for playing a bit of threat-roulette gives a nice burst of damage for those that watch meters, but it's akward threat bursts which can be hazardous at lower levels, and sometimes leads to the warlock tanking after about those 10 seconds of the initial pull. and also in most heroic runs if you don't give the tank about a 10 second head start to pull threat on a mob. it can be ridiculous.

strangely enough, the SoC shotgun can actually be useful in halls of reflection, the lower threat burst on the main target helps the tank and healers switch more often to pull individual mobs off aggressive DPS. though, its still ridiculous that conflag hits should out-pace a tank in threat. frequently.

in general, shatter is useless because of the fact that modern bosses don't favour a stand up fight, they favour elemental group tactics, current DPS gear has ridiculous crit and threat levels designed for nuking elites under 20 seconds. when a standard fight happens, people are really surprised when a rogue, lock, mage or especially a hunter in raid gear starts to pull right off the tank in one cast. other classes have threat mitigation, most locks cant afford the cost of shatter, or stand close enough for it to work, or wait the several minutes in which it can be used again

however, when i hit 101% threat in a PUG and get that warning note, the mental break of watching the casting bar for SoC to finish, allows me to partially relax, walk around the room a bit, do some laundry, make a small sandwich, dust bookshelves, check the mailbox, pay some bills, etc. but mostly lets me check omen's threat table, and that cooldowns aren't expiring before finishing up.