I've done experiments with changing it a few times, and I even took it off for a month in Jan. I had my most number of sales ever in Jan. when I had no banner at all. I really don't think it matters, most people come to my Shop from search engines, I don't think most of them ever even view my Shop. I had read something about the banners messing up the View on mobile devices, that is why I did my own experiment.