Hi - I am using a sys_editlivedynamic to allow users to enter some optional html. Testing this I found that the field value is never empty because RX puts in a div or p tag as soon as the box is activated. Even if I manually erase them in the code pane they return.
We had this issue when after upgrading from 6.5 to 6.5.1 and Percussion sent us a patch. You can also create a new macro based on #field_if_set that checks for the values that the control puts in.