For what it's worth - and I'm definitely no expert - I had a similar problem when rendering a procedural chrome shader I made. The metallic surface always had those annoying dots everywhere. I asked and some suggestions reduced them, but none completely eliminated them. I was told that it has something to do with the number of reflections in the scene. That basically Superfly was trying to do too many calculations and it was getting confused. Not to mention the fact that it also made the chrome surface look very glassy, too. It was really frustrating to me. I made some minor adjustments to my shader and re-rendered in Firefly and the problem was gone. I find anytime I render a scene, if there's metallic surfaces in it, I have much better results with Firefly. For cloth or skin surfaces, I like Superfly because of the depth of color it provides. Not really a solution for you problem, but just wanted to let you know someone else has had the same issue.

Here's the link to my freebies:   https://www.renderosity.com/mod/freestuff/?uid=493127

My cousin Jack can speak to beans. That's right.... Jack and the beans talk