I also think the scene creation in SU is faster than setting up the viewports in Layout. Primarily the reason would be a template in LO that has preselected tags set visible (using a proxy) is not as consistent as having them setup in SU as you may add tags that are not set automatically into your LO template.
While the model will obviously bring in any new tags you set in SU into the LO viewport, the visibility control would again need to be reset in LO. It is far faster to simply render the scene as established in SU. Now if we could just get a scene manager that allows grouping scenes and/or multi-lined scene tabs, it would really help.
The feature of tag control in Layout is excellent for my detail process, especially when you have one off details for a particular project. Also for presentations to clients it really speeds things up.