It would be nice to have a "format painter" type option.
It would be nice to have a "format painter" type option which copied/pasted properties, especially for ductwork. For example: click the paintbrush, select the item with properties to be copied, then select the item to apply them to.
You’re in luck! This is implemented and ready to go for the next release of DM HVAC. The beta will be available before the end of 2013.