I would use your 400 mh until the first day of flower. (I start mine 2 weeks in to help prevent stretch) The plants look great. I would not worry that they are not growing supper fast, they will soon. Your setup is nice and the plants look great. I would go back to the mh or your plants will start stretching creating a looser bud.
Nice job so far. Learn to post the pics in a thread so you can start a grow log.
peace