I imagine a lot of it is room, equipment and ear dependent.
In my apartment there was a wall about 3 feet from my right M80 and nothing to create a direct reflection for my left M80. I put a large stack of pillows against the right wall to simulate a panel at the first reflection point and felt the soundstage sounded narrower and less realistic. I switched and through up a piece of plywood about 3 feet from my left M80 instead and it balanced out the soundstage and made it sound wider and more realistic.
I also found with my QS8s in my apartment and now my house that having curtains 360 degrees around the room deadened much of the surround sound ambience though in some cases it does make discrete sound effects more precisely directional. I found that the loss of ambience far outweighed more directional rear sound effects. So in my apartment I would just leave the rear and side backs, behind the listening position, open to enhance the reflected sound. In my house I didn’t even buy curtains for the back and back sides of the room.
So IMO where the panels are located will determine what if any effect they will have on your QS8s. If they are up front to catch the first reflections off your main I don’t imagine they will have any appreciable effect on your QS8s.
But personally unless you have a specific problems you are trying to address I think treatments are a waste of time and money and may actually be detrimental to “good” sound reproduction.
