of starting an AoE grinding group,

Me and a RL friend are thinking of starting an AoE grinding group, with the intent of pretty mh AoE grinding instaes to level, with a pally tank, shaman healer, shadow priest, mage (either aane or frost) and a warlk. On trash, the lkmage DPS while the SP provides some support in the form of extra heals and a mana battery, then have all three DPSers do single-target DD on boss fights. I'm planning on being the warlk, whh for the purposes of levelling means I'll be spamming rain of fire on trash, and providing a lot of damage on boss fights. As sh, sie the primary fus of the build would be to irease AoE speed, I would want to irease my AoE damage potential (both the raw damage Ian deal, and the damage Ian deal without pulling aggro) as mh as possible. The sondary goal, where filler talents andor subsp would be, would be to have a fair amount of single target damage dealing ability, so that on boss fights wean still get through quk. It appears to me that an affltion sp would not be the way I would want to go. Until 70, affltion appears to have no AoE in it at all, and on 10, 15, even 20 mobs (we'll overpull a bit) tab-dotting wont do the trk. Thus, I am left between a 04021 build, whh would give me the ability to do rain of fire spam with my imp out for tremendous damage, or if healththreat isn't an issue Ian put him away for 15% more damage. On boss fights my gatling imp would do quite a bit of damageompared to a normal imp (over double if I did my math right) and Iould make use of SB spam. Or Iould go with a build that puts at least 41 points into destro, to get shadowfury, and then use a splattering of single-target fire damage on the boss fights. onsidering the mage will probably be using a fire sub-sp on boss fights, in this build I would get extra fire damage from him, and Iould swap outoS foroE. This depends on a few things...first off, if imp shadow bolt prs afft the shadow priest, I almost have to go with the 4021. If shadowfury does not provide enough damage to be worth it, 4021 is what I would want as well. I guess what I'm asking is this: On trash fights, how mh differee would there be in AoE damage Ian do with rain of fire (and shadowfury if spced destro) in the demo build or a destro build, and whh sp would do more damage? Assuming I'm levelling in instaes and have mainly instae blues to use. On boss fights, how mh differee would there be in damage Ian do with the two sps, one being SB spam as 4021, the other being fire spell rotation with a destro build? Again, assuming levelling in instaes and using mainly instae blues.