Motive: People often ask: what's the on the ground difference between projection A and projection B? (sometimes adding in a C, D & E too) Seems like a simple, easy, quick question to answer.
I am aware that you can supposedly do this by clearing the data frame coordinate system and reloading. However I get inconsistent results doing this, the program seems to be doing other stuff under the hood that I can't control, the data frame also sometimes gets hungry and grabs the first layer's projection. When I reassign a coordinate system to the data frame it sometimes refuses to resume on the fly and things seem stuck where they were no matter how I reload or restart the program. Meticulous note taking becomes needed after a transformation or two. This could be simple, it should be simple, QGIS can do it with one tick, Arc needs it too.