I see where you're coming from... But it is always handy to have at least one warlock that can self revive. It's saved my raid groups many times. Warlocks make good relic bearers in the vault because if they go down and the relic is dropped, they can quickly pull themselves back up and retrieve it. I, myself, use Voidwalker more. In the Vault though, I use Sunsinger frequently with all the teleporting and relic bearing.