I love this Idea too, I think it would be more easy to implement in a phone app :
- start a trace, show thé breadcromb
- show nodes and change the color or reached one
Today i used the breadcromb feature of the Sportstracker phone app to test this feature and i found it very useful to show your track and help to show where you have alteady been after lots of turns and turns.
Also I am less fan of automatic generated routes now