Heroic PvE is best accomplished by the "Holy Trinity" eg Tank Healer 3x DPS. The instances in outland were tuned for this setup, with hard hitting mobs, that require lots of healing, and threat control. Most have been done by 5x shaman teams, but that's a more "advanced' thing IMO. I'd go with the suggested 1 pally 4x shaman, and once you need a dedicated healer, spec one shaman into resto.