Tested a slightly longer gpx route with osmand the other day.
It has a major flaw in that the app is quite dumb when following a gpx route (don't know if it's a shortcoming of the app or the gpx format).
For example rather than saying something helpful like "at the roundabout take the third exit," it will say "turn left," meaning join the roundabout, "turn right," meaning go round it, and "turn left" again, meaning exit the roundabout.
Guess I'll stick to Google maps for now.