After @Daniel_Wright offered some clarification on the position of rough reflections in the lumen team’s priority stack, he also provided a CVar that I believe many will find helpful:
r.Lumen.Reflections.ScreenSpaceReconstruction.TonemapStrength can eliminate most of rough lumen reflections’ noise by (as far as I understand it) essentially tonemapping the problem away. Noise reduces significantly, enough to make almost any scene acceptable from a noise perspective, but it also erases a significant amount of detail from the reflection resolve. It’s probably the best tool I’ve seen for noise managment, however.
Sci-fi hallway example at previously established settings.
Sci-fi hallway example with r.Lumen.Reflections.ScreenSpaceReconstruction.TonemapStrength set to 1. Note the much cleaner resolve on the floor and metal walls (stills can’t really do it justice). This scene essentially went from unusable with lumen to acceptable. However, almost every specular highlight has been dimmed, and bright spots in the reflection are largely absent.
This CVar is a very good tool to manage noise, but like essentially everything else on this thread, it’s a tradeoff. If you need noise-free reflections and don’t mind the loss of detail however, this is a potential solution.