The issue that traveler
pointed out was that I tested if a key existed when I didn't need to. Only when the user defines the -u option is it necessary to test for the hash key's existance. Without the -u, there is no default condition and the exists can be avoided. I corrected the template accordingly.
You have mentioned an alternative way of determining which sub to dispatch. Unfortunately it may actually be less efficient than exists. You are fetching the value and testing it for truth where exists need only check to see if the key is present in the hash.