I understand that save as and save copy as do two different things.
One saves the document as a IDW or DWG with a new name and the other essentially exports it as one of many extensions.
But is this really necessary? I actually find this quite annoying when I want to save as DXF because I press the shortvcut for save as and then I have to quit it and go to save copy as.
'Save as' and 'save copy as' are essentially the same function, you are saving it as a new document so I don't really see the need to have two commands for this. If 'save as' defaulted to dwg/idw but you then had the drop down menu to choose dxf etc, it would be much more productive.