Multiple locks are sexxy. I ran with a spriest and 3 lock group up to 55 before wrath, and it was really fast and easy. Afflliction with 3 voidwalkers and shadow priest healing return is able to take down a ton of bosses easily. I have an 80 lock I'll probably go demo and match with the 55's to tank through outland and into northrend, but after that, I'll switch him out for a real tank and spec the priest disc or holy. Affliction is also a pain to macro efficiently, there's a ton of CD's to watch on longer fights. For leveling everything dies so fast it doesn't matter, but for bosses you lose a lot of dps letting dots drop off and meshing CD's. I'll probably go destro at 80 because of this, I'm more comfortable with it already and it's much easier to macro the sequence without overlapping or drop off.

I can't wait for 4x seed of corruption though. send pet, seed, tab seed, tab seed, tab seed, BOOOOOM. Do it right, and most of the trash would be dead right there. It's the reason I chose locks - because you don't have to "aim" a decently big aoe. I know there's mousecloner and such, but I've been able to box effectively without it and would hate to change up a big portion of play just to do some aoe.