I have enjoyed your story so far. It's been a fun read, everything from Harry-Narcissa dalliances to Harry's teaching. So it was with great hope that I opened the link to this chapter, only to feel terribly let down. Ironically, the best part of the fic is the most disappointing aspect of this chapter.
I too believe in the fact that it's the intent rather than the magic itself that determines how a spell is viewed. But your explanations for Unforgivable curses, it turns out is pretty superficial and fails to consider the depth of issues that one must deal with when it comes to unforgivables. Take the killing curse-the argument about the healers developing it are old and quite mundane, but those familiar with healing or medicine know that where euthanasia is allowed, Doctors rely on specific and fast acting chemicals to put patients to sleep.
In Harry Potter series, it's been well known that there are poisons and potions that kill in an instant and there is no reason for the healers not to use the same. There would have been no need for a healer to develop killing curse when they have effective means available, especially when the "brainy" healers would have foreseen the potential for disaster with such a tool in wrong hands. Imperius curse, now the deranged person theory too fails to satisfy as there are several ways to subdue a person without controlling their will the way imperius does. Healers who are much more familiar with potions, would have suppressants and controlling potions to take care of situations like these. Again the "brainy" ones would have foreseen the disastrous possibilities. Your comparison of cruciatus with CPR is akin to comparing a mild shock to a 20,000 kV electrical discharge. There are other ways to stimulate nerve endings than incomprehensible pain.
The one thing to remember about the unforgivables is that they are based purely on the intent of the caster. A person MUST intend to either control, inflict pain on or kill the other to cast these curses successfully. How many healers are capable of that is anybody's guess. It's not to say that the curses should not be used at all. The should be used when faced with evil, it's fine for people to use them in self defense or against threat from terrorists such as death eaters. they are what one calls a necessary evil and not harmless spells that were put to a bad use. Similar is true of spells like Bone exploding curse or Sectumsempra. You use them when your life, your freedom is threatened, but doesn't take away from their basic nature.