Looks like a nice little charger there. Let me know how it works if you decide to do with it. I think a charger is definitely worth it, if only for the times that the unit gets accidentally left on overnight or the unit you have isn't getting great battery life.
I'm suprised to hear that 5-6 hours is average for typical use. I have the cadence and HRM options as well. Perhaps i should just thank my lucky stars I'm getting such good battery life. A couple of questions:
1. Did they say how long it would take them to repair the unit if you did send it in?
2. What sort of recording interval are you using? I'm using the "Smart recording" option.
3. Is the firmware up to date?
One other observation I will make about the computer is that the speeds and distances reported by the unit are consistently lower than that of my riding partners. I'm not sure if this is because my riding partners have their wheel settings off or if the Garmin's Smart Recording interval has a greater margin of error. I would think that the speed being reported is more accurate than the wheel calculated models but I don't know for sure.