I can get Garmin MapSource TOPO! US 24k Southwest on Amazon for $88. I have a 62s Garmin and have been taking advantage of the free topo maps provided by GPSFile depot for the 4 corners states. Can anyone advise if purchasing this Garmin Southwest Topo DVD will be of any extra use over and above the GPSFileDepot maps for the same regions or is it just duplicating what is already here for free or donation?
While I cannot speak for the SouthWest, I can tell you I have tried every NorthWest Topo on GPSFileDepot and compared them to the best Garmin has to offer, and I found the NW Topo to be far superior to the Garmin 24k of the same.
My understanding is that the Garmin Topo will allow for automated routing, and none of the GPSFileDepot maps have this function. Unfortunately, the only way you will likely know which is best for you is to get them all and decide after you have spent some $$ and compared them to each other.
What is your primary use for the Topo and your GPSr?
As babj615 posted, the Garmin product has auto routing. It also has a grid of elevation data which can be displayed as 3D shaded relief and gives the elevation at the cursor. It will also add the elevation data to track points. The 3D shaded can be displayed without the Garmin topo being displayed (i.e. with the various mapsets available here).
Desert Southwest has autorouting and 40' contours based on a 10 meter grid. Street routing and address search aren't in CNNANT's class, but it's free, and covers the western 2 Corners. Main purpose of the map is routable trails. It also has land ownership data.
Nothing in Colorado or New Mexico yet.