Well, of course, "they are not as good as your 803s!"
Look how much r & d went into just the cabinets of the 800 series.
Why would you expect a standard wall to function the same?
The 8NT is a great in-wall speaker, especially, considering, it uses your builders standard drywall-2X4-crap for its box.
I still have not heard any in-walls that sound better.
I have 2 pair of 8NTs and a pair of CSW DS8s which are working great for back/surround.
I also have 12 more pair of various B&W in-wall/in-ceiling models throughout for whole house and back/surround.