I have the Edge 705. Though I haven't really used it for turn by turn guidance for rides/tours (except to find groceries), it's invaluable to me for the map view. There have been a few times when the route I plotted on my printed maps caused me problems and the flexibility of being able to scroll through an area helped get me on another track. I'm uncertain about the battery life for the Edge 800, but a small Solio charger kept my 705 going through 2 full days with power to spare.