Lastly, NAVAir uses large finger tip size touch screen buttons that I can always hit accurately in the worst of conditions. There is no fumbling around or trying to pick at small menus with a stylus. So for me, reliability and a friendly user interface are the main things. I want to keep my attention focused on flying the airplane, not playing with gadgets and NAVAir does that for me now. That is not to say that I will not be interested in a PC derived system with an altitude capable "solid state" hard drive. But right now NAVAir keeps me out of the weather and that is my primary focus.