Just for fun I just tried turning up my gfx settings and turning on steam's fps counter. I was actually in the 30-40fps range with my machine lol. And I then tried turning on/up some settings and stayed in the 30fps range with medium settings. This all worked out way better than I thought. Cross-posting this to performance thread.
Now back to gameplay talk.
Run 1:
I went back to Final Test, turned off all of the HUD stuff except for Attention and NPC Icons and tried to SA+SO my way through as my second playthrough of that mission. It all worked out quite well, didn't even need to take out the first guard but then I got distracted by the Chess game on the table and the target and his escort walked back in so I knocked them out quickly, snapped target's neck and dumped them in the box in the bathroom.
Then tried sneaking my way out but that guard at the stairs noticed me after I snuck past him and did the coin thing with the two guards in the room below so I had to knock him out as well to get rid of him. Managed to get through the guard room easily, though. Those coins really are pure magic. SA went out the window but at least I got my SO box ticked with some improvisation.
Run 2:
Went back, same idea but I wanted to do it faster this time, too. So I discovered the two talking mechanics at the start are essentially blind since you can just scale the fence even though one of them is pretty much looking straight at you but anyhoo. Crouch-running all the way to the drain pipe is fairly easy to do, too. You can do this all in the first cycle technically so that the patrolling guard starts walking back to the gate shortly after you arrive at the pipe. Problem is, those two mechanics then start interrupting this clean run with their scripted route into the hangar.
Screw that, I see and climb up anyway. Of course they spot me and, boy, will I be in big trouble later when mom comes home! I climb into the target's room and still knock out the escort guard, put on his clothes and dump him in the box. Meanwhile everyone rushes into the office and starts looking for weird that weird dude who climbed around outside. I walk past them, trying to find the target and get the "shoot him while disguised as an officer" challenge in this botched run but I lose him downstairs since I'm not familiar with his escape route/script yet. And to top it all off, I run straight into one of the guards who sees through my disguise and I die in a shootout in the office area downstairs.
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So I guess that puts a nail in that "you have to reload or the dumb AI is just gonna stand there and let itself get picked off one by one" / "escalation recovery isn't possible/sucks" argument.
Even this simple prologue mission lets you not only approach the target in numerous ways, you can also experiment with recovery/improvisation/escalation/optimization a lot already. To me, all of this suggests great things for the final game.
funnily enough, I answered this while writing this long ass post
see "Run 2" paragraph