@GeorgeK I haven't had time to document some of these issues just yet, but I will ASAP.
I also noticed that the high quality blending is very noticeable in layered refractive materials with bump, possibly refractive materials with bump in general. This actually isn't all that surprising because the seams of the tile blending create enough regular noise that must also be refracted, as to be noticeable. I'm not sure there could be a fix for this given the current implementation, i.e. the shading is rendering correctly, it's just that the blending method is so noticeable in a refractive surface.