We are also dealing with a (mechanical) party which only delivers navis models.
They put models together in Autocad from several suppliers into one very large navis model. Importing the dwg files into Revit is not possible (while Revit translates building elements but not all 3D Autocad objects) and converting to IFC takes 2 days work (for every update!). So using the coordination model is the only way.
Not able to show my client what his project is going to look like in Enscape now - worthless.
We HAVE to take our client through the navis model now which is a real pain