I agree but it could be several things going on with my tests. 1. I did get more than a full charge from one. It could be that the battery in mine was able to take more charge than listed. Flying model planes and using decent batteries this is often the norm and not the exception. The meter on the phone could be poor or it is easy to put a little energy back in when the phone is low and have the meter read than when almost full so the extra I got in on the second partial charge probably was really less than indicated.

In the end, I got to have a phone recharged fully one time and had a little left to spare to charge some more for an emergency. Not sure many need more than 2 charges when riding.

As for waterproof, etc., you are totally correct. The Garmin is made to be out in the elements and even if it does fail, you might still have a phone to use. I say might because most put their phones in their back pocket and many here say in an accident, things in the back pocket can be damaged or hurt you so I am not sure what is the best place to put a phone. Mine stays in a Timbuk2 Goodie bag and the charger beneath it sitting on the top tube. I don't think there is a good place for most stuff when riding.