So I was trying to figure this out.
Why does someone play a shadow priest in favor of a warlock?
A warlock is a pure class, and thus will always be designed to do more dps.
Warlocks have a DOT spec, like the shadow priest spec.
Is it because if you want to, you can respec and heal?
But Muqq of Ensidia is shadow/shadow. I don't think I've ever seen him with a healing spec. So why does he do it?
So if someone is just looking to DPS, why would they roll a shadow priest over warlocks?