with the nat geo maps you can still down/upload tracks, waypoints, and routes to one another, you just do not have the topo info on the screen. We record everything for the day, tracks and mark all sign then take it back and load to the maps to see exactly what we have done and what is there. We can then clear out tracklogs, and misc waypoint data that we dont need on the gps proper and have a clean unit for the following day. If there is info that we will use the following day that of course is saved on the gps. The entire thing is saved on the map asa file and remains intact until the season is over. That is when I take and archive the data (merge it into a master map) sounds like alot of work but is really very simple. You can also see what the other hunters do and you will be surprised at how far you did not walk during a given day even though your legs are tellin ya 4 miles you most likely did 2 on the gps. If you do go for the NiMh batteries check out www.sunbattery.com good deals, good product. Get to know that unit real good and by all means dont make it your only source of nav aid, Keep and use the compass and map as you always did, MURPHY LIVES