[Anvoker]

Are you sure that the jankiness you describe is not related to you not being close enough to the enemy for it to count as a point blank hit? The engine does a simple distance check which is rather unforgiving, and if you utilize the range your melee weapon affords you, you will fail this point black attack check. This is just a guess on my part, but it's the #1 reason I've seen people be perplexed at seemingly inconsistent melee stealth takedown behavior.

If you first push yourself as close as you can get to the enemy model and attack the general area of their torso, it works every single time. But again, this is just me taking a guess as to what the problem you're referring to is!

[LarsDu88]

Well that's the problem. In the first mission you have to figure out to stun the enemies in the center of their back rather than directly in their head. Its super counterintuitive and probably leads to many players not getting past the first mission.

It makes the difficulty curve super inverted

[SJC_Hacker]

Only if you want to do totally non-lethal and "ghost" playthrough. Even then you have the dart gun