warlock specs in 10man raid``

hi, im in a 10man raid guild that is starting to do heroics..
our core team has a lot of caster dps, 2 mage, balance druid, warlock ... also a dk and a rogue..
so since we have a lot of casters and no elemental shaman, would u suggest that i go for demology for all bosses? even on fights where demo is not so good compared with the other specs, aff/destro.
or would u suggest that i go for the spec that can max the dps output and survivability (for warlord as example, i think if i go destruction, netherward would a very good skill, can decrease the pressure of our healers a lot..)
thanks ``
our core team has a lot of caster dps, 2 mage, balance druid, warlock ... also a dk and a rogue..
so since we have a lot of casters and no elemental shaman, would u suggest that i go for demology for all bosses? even on fights where demo is not so good compared with the other specs, aff/destro.
or would u suggest that i go for the spec that can max the dps output and survivability (for warlord as example, i think if i go destruction, netherward would a very good skill, can decrease the pressure of our healers a lot..)
thanks ``