I've got one just like it and it is excellent. Seems to work real good in woods also. I have been scanning old maps into my computer as a jpeg file and then download them to Google Earth as an overlay. You can rotate, shrink, enlarge, and ghost them to fit after downloading and then able to see old sites on modern aerial photos. The mouse pointer hoovering a spot will give you the coordinates at the bottom of the screen. These coordinates can then be input as a waypont on your Garmin. With that information you can go to the waypoints in the field that you stored to do your detecting. Oh, I forgot you can set an alarm to go off when you walk to a set radius of your waypoint. Make finding old spots a bit easier but remember accuracy only as good ad the person that created the map you use as your overlay map.
Bill