K, I did the stats on maxdps.com and here is what I got. I put 1k damage on all, and 100 hit rating.

Group 1 - Shammy healer, pally, warlcok, spriest, mage.
Class - DPS
Spriest - 860
Lock - 1332
Mage - 1055
TOTAL DPS - 3,246
(But maxdps didn't factor in ISB from the lock, so that would add a few dps. The pet would do some more dps in lower level instances as well.)

Pros: Healthstones, soulstones, misery, shadow weaving, constant mana + health return from spriest, pet from lock, chain heal, earth shield. (any others?)
Cons: Not alot of burst dps, less buffs, no moonkin aura. (any others?)

Group 2 - Priest Heal, pally, boomkin, mage, ele shammy.

Class - DPS
Mage - 1,056
Boomkin - 933
Shammy - 1,278
TOTAL DPS - 3,267

Pros: Totem of Wrath, Grace of air, thorns, MoTW, Moonkin Aura, druid can off heal if needed, lots of HoTs, treants, b rez, CL, Innervate. (any others?)
Cons: Priest healing would be harder, no SS, no chain heal. (any others?)

Pretty similar.
Can't decide yet :S