You've got sustained dps, burst dps, survivability, healing, utility and cc to play with when balancing classes. Right now I don't think a sin wins in any of those categories save - possibly - survivability. Of course survivability is the absolute worst of the 5 dimensions for balancing so it needs to be a HUGE difference to mean squat. Unfortunately I'd say healers - just by virtue of healing themselves - have more effective survivability anyway.