I use the Lowrance unit with the 6 inch screen. It is primarily used to nautical navigation, so has full 3-D underwater features shown, Google Earth style. I bought a map of the western united states,, on micro sd card, it is super cool in that it shows all the tiny elevation details, even so detailed that even though it does not show smaller roads as colored lines or callouts(it DOES show major roads and all interstate and local highways and county roads), it shows so much detail in the ground that you can actually see the lighter and shadowed shapes which match up to graded road surfaces, culverts, and even shapes of buildings and structures! Super super awesome, It is shaded in realistic ground/mountains colors, so it really looks like a simple version of Google Earth in terms of color detail, with the addition of the crazy detailed topo, which I really must assume is a result of a radar from space generated map in terms of elevation detail.
We do a lot of offroading to get to specific old mines, or mineralized areas of the desert, where there are no roads to, and it is awesome to be able to see and identify washes, obstacles in the path, etc, all on the gps topo virtual generated view, before we get there... i WOULD SUPER RECOMMEND IT IF YOUR MAIN USE IS TO GO WHERE THERE ARE NO EXISTING ROADS, IN MOUNTAINOUS OR RUGGED AREAS.
