So I've been looking at the various options out there for trail riding GPS units, and short of spending an arse load of money, I'm looking at downloading the Gaia GPS app on my old iPhone 4S that I no longer use. I can download the app for $20 when connected to WiFi, and then all USGS topo maps are free after that. With this being a true GPS app, cell service is not required as it runs off the GPS chip in the phone. Supposedly this and MotionX are the two best GPS apps for the Mac platform and the only negative I have read is that the topo maps don't have crazy clear resolution. The main key I like about it is the "breadcrumb" feature which lets you plot out where you have been. This way I could just cruise some easy trails close to camp to get a visual alignment to the trail maps and then explore my way out from there without trying to remember which way was what. Anyone try this app before and if not what are you having success using?