Don't get me started on SkyDemon, I don't use it, most of my flight planning is done on the tail plane. Like anyone else that gets the licence, a GPS thing is the first toy to buy. As for missing something, like what for instance? Because with my Runway HD or any tablet based chart you can zoom in to have a close look as you wish.
If someone draws the line right through the altitude of controlled airspace and misses reading it, serves them bloody right.