Thinking of getting an edge 800 performance and map pack from Wiggle, I was just wondering though is it actually worth paying the extra for the maps? It says it comes with base maps but what are base maps? I get the impression they are basic maps but just how basic is basic? When doing organised rides they always seem to go on small quiet roads, can I presume that these are not on the base maps? I'd just like to have some idea before I splash the cash!!