Sorry, I should have replied sooner. You are both right of course, the symbols are the same size. It was an optical illusion due to the shape of some of the area fills in the original survey (http://expo.survex.com/expoimages/surveys/107-plan-2013-draft3.pdf), and once I could see it there I convinced myself it was true in the cut down example as well. Sorry to have wasted your time!