I've been in all four of the category 7 cabins right across the hall, 7622-7628. I like this location a lot. There's very little foot traffic or noise. You don't really hear the engines that high up on the ship. This is actually my preferred location on the ship. The aft balcony of deck 7 is right down the hall, and it's convenient to the aft stairs/elevators, so it's just a quick run up to get coffee or grab breakfast at the buffet.
As far as motion goes, everyone's experience is different, but I personally do not feel the motion more from fore to aft. I do feel it more the higher up on the ship I am, but then only slightly so.