Hearing what you said makes me really want to play the game now, games aren't balanced around easy mode anyway so this is all good. Lights off, hard mode on, oh boy, this will be awesome. Co-op mode seems to be a nice addition as well. Do you have any other games you can recommend with the same kind of play-style? Constantly having to be aware that some creep is popping up out of the nowhere, minding your ammo, stuff like that?
Metro 2033 falls into that category and its sequel is due out in a few months (although not near as much popping out of no where as the Dead Space series)