The primary interest is not navigation it is - for short periods - the ability to "stack" the maps to pool all the POI's together for far deeper and more effective searches which I find very useful at times. The POI's have always been quite different between Topo & CN, but now also between the differing CN's. To me the benefits of this far outweigh the risk of a minor blip at the time, maybe not everyones cup of tea but I'm sure there are others who would also find this a useful technique. It's one of those little things in life you don't really appreciate until you try it.