I noticed the new manual example and tested it.

dist_ahead = sign(dist_ahead)*(abs(dist_ahead) + 0.5*dist_down); // adapt the speed on slopes

I don´t like the behaviour this line causes. It causes jerky jumps when going over stuff like stair edges.

And if I add move_min_z = 0.5; to prevent going up steep slopes I can move into the geometry of ramps and get stuck there if I glide along their sides. (I mean a ramp like on the screenshot above.)