I am able to navigate a course that i have uploaded via a GPX file or ridden in the past, but there are no alerts if you are off course, or going in the wrong direction (for 11 miles as i did). The best I seem to be able to do is to watch if you are on the purple line. This requires having the screen on all the time or checking it regularly which is not practical bike packing.
Is there any way that the device can let you know if you are off course (my 820 does this somewhat well, and i was hoping that the 66i would have it nailed).