The interaction with characters may be different but from what Ive seen, the end result of each talk is about the same, just with more attitude behind the characters. As for the end, I was super light when I hit it and if I chose to be dark (purposely short on details to spare spoiling it for anybody playing through the game) it put me at even or 1 point towards dark. When I chose light it just kept me at my super light rating.