Frost DK brings WF, and a marks hunter brings 10% AP. Now I heart my shaman and his is relatively well geared/played (gs 5400ish) - but in top tier guilds I notice that enh dps is substantially below the "primary dps" roles, that there has been discussion within more than one guild about replacing that slot should their enh fall over dead/quit etc. So really the pondering question is do other two classes filling those buffs, even though their spec is not optimal, still have the potential to do more dps than the enh shm?