About an hour in to the mission I discovered that Nazis are actually kinda dumb and you don't really have to be very careful at medium difficulty.
Also, i don't understand why there are non-lethal options in this game, but I suspect there may be liberalism afoot.
I should note - If I did knock a Nazi out I specifically went back and shot them in the head. Those ten guys were accidents. Would have gotten them if I could.
In the multiplayer to one of the Splinter Cell games, Chaos Theory maybe, one side played like an fps and they were mercenaries with lethal guns. The other side were ninjas in third person who had smoke bombs and you could bug their communicators and such. If you were a ninja who successfully snuck up on a merc you could get them in a choke hold and talk to them before you killed them. Apropos of nothing, really, but I really liked that game and wanted to talk about it.
Yeah I thought the non-lethal stuff might allow interrogation or something, so I tried it. No dice.