Disclaimer - I don't do a lot of touring, the bulk of my riding is commuting, or weekend fun rides. I have an edge 800 which I use primarily on my fast weekend bike.

I live in San Jose, and when the NAHBS show came to Sacramento a couple of weeks ago, I decided to ride up there, which was a 2 day ride. I planned a route, balancing what I thought would be pretty with the total distance etc. Had way too much fun making all of those decisions. Anyway, on the second day, I am riding along and my route has me crossing a river on a bridge - and when I get to the bridge, it is closed - it was all wrapped up and they were removing lead paint and repainting it. The workers advised me to go back 8 miles, cross the river at the next bridge, then come up the other side of the river - which would have added 16 miles to what was already not a fun day (I was battling headwinds all day long, and was much later than I wanted to be at this point.) Long story short, just punching my destination into the Garmin 800, it recalculated the route for me with no problems. I could have done the same thing with a map, but the electronic version was definitely very easy.

The batteries last plenty long for touring, assuming you have a way to recharge overnight - I have never had mine die during the day, and have had days where I was riding for 12+ hours.