In the interest of accommodating all unit preferences, I've made sure to use dim nodes for all dimension values. So far this works perfectly if I change unit preferences inside of my working document.    If I create a new imperial document, I can import and operate these object nodes perfectly.  If I create a new metric document, they do not even appear on the design layer, and the Shape pane in the OIP shows me nothing aside from that there should be 'something' there...