I have been rolling a priest , mage and 2 locks for a couple of weeks (hand levelling a paladin atm to 5 box).

I has 2 x alli locks at 60 pre TBC & re-rolled horde on a new server with a lock at TBC launch, so I have a fair bit of /played on our favourite evil class.

I started off my 2 locks going for instant corruption (as any solo lock does) and thinking of dot powah!

by about lv 17 i realised that with the combined bolt dps of 3 offensive casters, dots are kinda a waste of time, I can kill anything my level with 2 sets of bolts (2 shadowbolts & a frostbolt). Mobs 3 levels up will drop to 2 sets of bolts and some burst (2 x shadowburns & a fireburst).

Basically everything dies before even a couple of dots tick twice so I respecd my locks.

One is going full destruction - maximum burst dmg - for a solo lock this spec is risky because a) you dont have improved pets to tank and b) you are pretty squishee when a mob gets to you, which it will because you cant kill it in time - however with focussed fire it will die in time and with another warlock....

VW tanking is adequate WITH TALENTS , and adding blood pact to a VW boost him a lot - so one of my locks went demo - 2 pts in imp healthstone 3 pts in The stam>spirit talent. Then 3/3 improved VW. Then into destro up to shadowbolt - You could then go back into demo straight away or do what i did and stay in destro until i get enough points to have shadowburn & a felguard (remember that a felguard doesnt have all his skills at 50 - 61 is the ideal level to switch over)

I think that for boxers who have the benefits of focus fire burst damage beats dots & longevity.

However... On my first lv 60 toon I was a huge fan of the SM/DS build - dot powah with a sacrificed VW to regen health>mana - warlock aoe farming back in the day basically consisted of running round in a big circle training up to 15 mobs at a time fully dotted up leaving a trail of corpses - the build went out of fashion massively with the changes at TBC but a modified version consisting of 2 + locks at a time is something i will definitely experiment with down the line - for levelling though u got to love a big Blue tank & the burst dmg!