I would definitely advise to stick with the GUI tools, because for Activiti they support (most of) the BPMN that the Engine supports. So in most cases there's no need to write it in XML. What kind of BPMN elements do you want to use that a GUI tool doesn't support right now?
I'm getting more comfortable with Designer now. I'm new at this and just trying to get an idea of what people are doing so I don't have ideas about what elements I might need that may or may not be supported. It was just a general question. Thanks kindly for the response.