If we could reliably know these scenarios in real life, there'd be rules about them.
I am reminded of the idea that extraordinary claims require extraordinary evidence. Living without rules is like playing chess without knowing the games ins and outs. Youl'll probably lose most of the time to a more skillful opponent even if you manage a lucky brute force win every now and again..
Killing Hitler sounds like "act utilitarianism".
It seems like an extraordinary claim that we could know precisely which specific act to take in reality rather than thought experiments -- and we act within human reaity, not some fantasy alternate with psychic powers. Its therein that morality has developed.
Or an example of Kohlbergs "postconventional morality", maybe?
If I wouldn't kill Hitler its because the law "don't murder" is there for a reason. As in rule utilitarianism, which deals with types of actions I think, as a means for the social programme.
Its a bit like I might chop my finger off so that I could buy a winning lottery ticket. Ok, sounds like a possible beneficial trade off, but we live by rules for a reason. We have evolved to live by rules for a reason, its called "conventional morality" and we are integrated into society with general rules style thinking as teens.
Lawrence Kohlberg's stages of moral development - Wikipedia
We have sensible but fallible everyday tactics, geared towards a reasonable strategic end. And the meta-rule, i.e. don't breach them even if a breach would profit from time to time.
"If thou be the Son of God, cast thyself down from hence: For it is written, He shall give his angels charge over thee, to keep thee: And in their hands they shall bear thee up, lest at any time thou dash thy foot against a stone." (Luke 4:9–13)
In Christianity there is a vice called tempting God, ie relying on Gods mercy to extricate us where common sense ought to prevail.
Dictionary : TEMPTING GOD
Killing Hitler may sound good, but in the real world such actiona are as silly as jumping off a cliff.
Whyetr the wuuyt.