Sorry there, by "App" that does topo maps I am referring to the smartphone (iPhone) only GPS applications.

My phone (Palm Pre) with Google Maps is currently telling me I'm over a mile from where I am. It's either the only cell tower in town, or perhaps the center of this small town. In the city, it works great. I can walk along the sidewalk and it is extremely accurate. I don't know that I would trust a cell phone's GPS outside of the multiple tower aGPS zone.

Another question about the iPhone GPS: Doesn't it require a data connection to actually get the maps? I believe I read that only the TomTom app actually stores maps on the unit. It also costs nearly as much as a standalone GPS.

Phil, my 4.3" Nuvi 255W was stolen a couple weeks ago. I just replaced it with the newer 5" Nuvi 1490T. I had some luck getting the Topo maps into the Nuvi 255 before it was turned into someone's crack money. I'm hoping to do the same with the 1490. Found this thread of info: http://www.gpsdiscussion.com/garmin-gps/7086-garmin-nuvi-1490t-topo-maps.html

The 1490's large screen and topo maps would be a great trail GPS.