I have the GUI downloaded to my computer but I've never seen the need to use it yet. As CraigCam says, probably the main reason for using the GUI is to set your default height and smart mode limits at user values. Since I also use my H for commercial stuff I have to keep it within the CAA 400ft limit for standard PfCO to stay legal, Because of that, then, I have no cause to alter the height that my H can ascend to.