I don't really believe that there's a single person on the face of the earth - not me, not my mother, not my former boss the Quaker - who couldn't be induced to kill someone or do a similarly evil action under the right circumstances.

This is very true, and this is why I also don't have a problem with thinking "Draco can redeem himself" and "Draco's done some pretty god-awful things" at the same time. I don't see that his actions put him in a class separate from the rest of humanity. I think Harry would probably do similar or worse things, given the right situation. It doesn't make it any less wrong, but it doesn't nullify any potential for good Draco might have.