I'm thinking of getting a GPS unit that I can use on my bicycle, hiking and canoeing trips. I've narrowed it down to the Garmin Marine (waterproof/floats)GPSMap78s or the Garmin Land (sinks but waterproof) GPSMap62s. The 62s has a bicycle handlebar mount.

I already have a pretty good bike computer with elevation and heartrate. It only gives me totals and averages. I can't plot my rides...but I don't really care to.

What is your experience with GPS? What unit do you use? Is GPS worthwhile for a cyclist, or is it just for techno-weanies?