Richard
I successfully used a pdf map for St Malo to Nantes on a recent tour. the display of minor roads proved very useful. Certain pages were more useful than others; when the route was NW-SE, NE-SW or W-E there was sufficient map displayed but when N-S the map was very limited (look at the final page into Nantes).
It would be helpful if you able to adjust how much map is displayed.
cheers