Not sure if anyone has noticed this yet, but on levels such as Three for All and The Trace, you are able to jump onto guards that haven't noticed you, long after they should. Doing a bit of testing I found that it's because the door that flies out of its frame once you've kicked it open stops any guard from seeing you, including Enforcers, Professionals, and The Sniper, not just the normal guards.

You can see this by the fact that only after going past the knocked-down door (towards the guard) will they see you, but you can become "hidden" again by stepping back behind it. Then, once they begin to patrol and pass the door, they'll see you as per usual.

Can't think of anywhere this could be applied within current NG+ runs, since they've either implemented them already, or would be slower with them included, but I don't run any other cats that could include this (yet), so I figured I might as well bring it to light.