@Corjan-Meijerink 
I liked the way how RMA picks up the route again after deviating from it and the option to keep the original route visible on the map.
It seems that a route cannot initially be calculated without internet connection, as also indicated by pop-up messages. Once calculated navigation works with the installed local map and local route data.
However a few times the navigation went wrong (cannot calculate the route and once the position indicated on map remained some 500 meters lagging the real position). I don't know if turn indications also came too late. Restoring internet connection for a moment solved such problems.
On days with permanent internet connected there were no issues and data consumption was between 75 MB and 150 MB per day.
All together RMA left a positive impression with me and probably I will use it more often to get better knowledge about it.
Your information about 'by design' I don't really understand yet.
What are the advantages of it ?