I have a Oregon 400t unit, and so far have had fun using the preloaded map. I have sucessfully loaded my area geochaches onto it, and it is great going "paperless" while tracking down caches. After I'm done, I go in and delete the files with my computer. Now I would like a more detailed map for hiking, so I ordered the micro sd topo map for the mid atlantic region. Will I still be able to download geochaches when using this map, like I do with the unit preloaded map, or will I have to take out the SD card and just use the included map ? Thanks.
