We also have the instant death if head, chest or abdomen is severed rule. But we allow for the body to be repaired by a Heal 6 or Heal Wounds (with at least 6 points of healing) if it is done within 5 minutes. This means if you really want someone dead, you kill them and take their head.
We have had a few deaths where their stats degraded to the point where they could not be resurrected by the time we got them to a healer. Also there is the requirement of a year and a day of service to the healer after resurrection.