A couple of points worth mentioning about Disguise - which weren't mentioned by anyone else yet...

1. You use Disguise AFTER killing, not while they're incapped.
2. The person you're Disguised as can identify you no matter what their class.

Also, does anyone have any interviews or previews confirming that Operatives see through disguises? Because I'm pretty sure I've only seen that information on the forums, and while it seems to make sense that Ops would do it, I remember reading in an early preview (I think it was IGN) that ONLY the person you Disguised as can pick you out.

Interviews awhile ago. Nothing recently.

Well I know my source is from an old build of the game, so I'm curious which is going to be true - I'm not concerned either way, but either option leaves the Operative in a powerful position - either because you can hide no matter what class your enemy is, or because you're useful as a defense against enemy Operatives.