I am a big fan of the check in the dark when OOP. Since there is no such thing as a check in the dark in online poker the insta check is plan B. Speaking as someone who is an insta-checker I have found the check in the dark OOP to be a profitable move as I can get out of hands very easily if I missed, but if I hit [or successfully bluff] and have checked in the dark [or insta-checked] the success I have had makes the move a profitable one. My opponent never knows if I hit or not until the turn. If they don't want to risk being pushed out on the flop [since betting is typically a 50/50 gamble] I get a free card on the flop and a better understanding of where I stand in the hand come the turn.