I've also moved pretty far from non-lethal, as popping skulls with the pistol is too much fun. Silenced, lasered pistol from cover to the brain - so satisfying. I had one point where I was stubbornly trying to go out the front of a building rather than the lengthy vents I'd come in, and just kept popping guards. They kept coming up the two sets of stairs, which were littered with bodies (oh crap, a body!), I kept popping them in the head. What I didn't realize is two were on the roof above me, and when I finally thought it was over they noticed me and gave me a quick death. So I gave up on that method and just found yet another exit.