It is something like whether multiengine are safer than single aircraft. Obviously, the more engines, the more likelyhood that you would have an engine failure. But the actual safety factor is determined more by the skill of the pilot to handle the situation. A good raid 1 configuration doesn't eliminate the possibility of a harddrive failure, and actually increases that factor, but it does increase the safety of data, if the administrated properly. If you have no faith in yourself, then perhaps a nonraid system is better. You do not need to be a PC guru to accomplish this, only a careful and alert operator.