From what I've gathered if you use a mat you're going to be able to cut your frequency of flooding down a little. The applications of a mat that I am aware of are more for plants that REALLY need a lot more moisture. Personally I would not go that route because it is unneccessary and doesn't allow you to move plants around in the tray to pick out dead vegetable matter or treat for pests. BUT I am not growing in hydro at the moment and do NOT consider my self close to an expert! lol! To me the number one thing is being able to keep your setup CLEAN.