No solution for viewport, at least at the moment.
For rendering you can just subtract the specular light pass from composite, denoise it and add it back in. The denoise node could add significantly to render time. If there’s a faster way to filter while preserving edges I might add it as a automated option to the addon. I’m currently not very familiar with blenders compositor.
Not sure if it will hold up for animation. From limited testing there were also some artifacts along edges in front of the world background.
I want to look in to ways to improve that part in the future, but I have minimal hopes for fixing it in the addon only version. That same noise pattern can be visible in default eevee renders without doing anything incorrect with the render settings, it’s just way more subtle.
@wev It is compatible with 2.9.