Metalness workflow is binary and not suited for subtle detailing of materials that blend metal and non-metalic surfaces. For instance, it’s extremely hard to add occlusion dirt to objects with metal, as the partial and subtle blending of metal and non-metal surfaces results in washed out / white fringe artifacts. A full specular color workflow as implemented in for example Marmoset, would be much better for this subtle detailing of metal surfaces. Just add a new shader variation next to the metalness one that supports full colored specular workflow from Substance painter and similar to the Marmoset specular workflow.
Someone else explained it here too: