It's at 0, but I'm told to lower it for clear reflections? So does that really mean negative values? And to where? This slider has always been unforgiving and strange, and now things are weirder with two very different results between standard and path traced. There needs to be some uniformity here. It really should be just as reflective as Standard Renderer, making actual use of the roughness slider to obtain rough reflections like in Path Tracer. It was mentioned probably couple years ago that the value threshold would be fixed for Standard, too.
With how rough PT reflections are, that should be 1 on the roughness slider (of course allowing overhead for more blur).