My favorite current GPS for Mexico/Baja rides is the 60C. I can load in my Bicimapas maps via IMG2GPS, and then load my waypoints via Mapsource. And I still have plenty of memory for recording tracklogs. The 60C can be had fairly cheap. Best bet is to hard wire it to the bike's battery and NEVER run it with the AA batteries. The reduction in mass of the unit really seems to help also.