I too recently bought a pair of these insoles. At first I did not think I was going to like them because they seemed to reduce the volume of my NB 812's, making them seem slightly smaller. But I left them in, and after about two weeks' of daily wear, they sufficiently molded to my feet that I now like them. I too have a normal arch and have tried a handful of other brands, including SuperFeet, without success.
Even though I love New Balance trail runners because they do not require any breaking in period for me and do not cause me blisters, after a couple of hundred miles they begin to feel a bit "flat", losing some of their cushioning. I am hoping these insoles will help them feel supportive and comfortable a lot longer.