The ammendments to clearances that I have experienced tend to take the form of a radar heading and a different stop altitude/level instead of the original departure instructions or SID. Its not complicated to rebrief, very little if any programming required. In my company more often than not we will thank the controller for thinking commercially and take the ammendment.
Please continue to offer this option to us, some will take it some will not, but we appreciate being given the option.
Someones beaten me to it, its basic flying dont get caught up with your head down in the cdu and fly the plane. K.I.S.S.