I work in Film and Television. I have used Maya, Solidworks, Rhino, Sketchup, Autocad and a few other packages. I've abandoned all but Rhino, SU and AC. In my TV work we have to design sets, put out drawings, and get them built in days, and sometimes hours. For modeling, nothing is as fast as SU. Period! However, in my workflow, it is much faster for me to section through the SU model and export to AC than to use Layout. Layout just does not have the tools.
I will use Layout when I just have a small element to complete, and lots of time. Granted, I'm sporadically using Layout and by no means well versed. But even just moving around in Layout on my computer it is much slower than AC. I recently worked with someone who only worked in Layout and was considered fast with the program. I was doing the more complicated pieces, and my SU>AC export method was at least 2 twice as fast if not more.
Perhaps as I use Layout more I may discover methods that help me pick up the pace, but I'm still skeptical.