Don't they go away if you hook up a metal resource? ie as soon as bronze comes in you can only build axes/spears... works that way with every other civ anyways. In either case an axe is better, and axes+cover are way better than a quechua.
They kill barbs well, but with HC you're almost better off building the GWall if barbs are going to be a nuisance (1 GWall = about 7 quechuas... 4 quechuas if you have stone).
I guess in the worst case scenario where you have no metal and no stone and get beat to the GWall by someone (cough cough Qin) on a higher difficulty level, then yes HC is probably the best bet to have to beat back those annoying barb archers. Otherwise, still not that special IMO, especially since you will get eaten if you are neighbors with Alex, Monty, or anyone else with some extra axes they'd like to march over. HC seems to be unpopular with most civs for whatever reason