Dear Revit,
Please consider revising the underlay function to be more similar to ArchiCAD's "Trace & Reference" or add a new feature. ArchiCAD's feature allows users to select any view in the project browser and overlay it on their active view. This was an invaluable tool that allowed for simple, quick, and efficient coordination across different stories, plan types, and other views such as sections, elevations, and details.
Revit's underlay tool, which is the most comparable, is both too confusing to be useful and is incredibly limited. When making the switch from ArchiCAD to Revit, this is one feature that I miss dearly and makes my experience using Revit a lot more frustrating than it needs to be.
Please consider integrating a version of this Trace & Reference tool. I'm sure most of your user base would greatly benefit from it. Thanks.