The workaround works for me, although I didn't test it against a central file in a Revit Server environment as we don't use that.
Here is the simple bit of code that tests the central file type:
Public Shared Function ReportCentralFileType(ByVal _mpath As ModelPath) As String Dim strR As String = ModelPathUtils.ConvertModelPathToUserVisiblePath(_mpath) If strR.Substring(0, 2) = "\\" Or strR.Substring(1, 2) = ":\" Then strR = "File-Based: " & strR ElseIf strR.Substring(0, 3) = "RSN" Then strR = "RevitServer-Based: " & strR ElseIf strR.Substring(0, 4) = "A360" Then strR = "C4R-Based: " & strR Else strR = "Unknown: " & strR End If Return strR End Function