from the top of my head I can't think of a single corner in a comp map that you could take wide enough to not get into flamethrower range...
about holding S, maybe I'm just terrible, but when I do manage to stay out of range as scout, I'm so far away that i can do at most like 40dmg per shot while not seeing the pyro through the flames and having to know the geometry of the map backwards perfectly to not get stuck for a second and die.