How real is the Domefield advantage in the playoffs?

Probably about a FG worth. Maybe the noise causes the opposing team some confusion or a questionable call goes your way.
A lot of people don't remember, In the playoff game vs the Vikings, the play prior to Brett Favre throwing an interception they Vikings got a 12 men in the huddle penalty. Was the crowd a factor... maybe? Additionally there were two "'50/50" calls in overtime that went the Saints way.