Similar experience with the Edge Touring.

I now use a Samsung S5 (water resistant) mounted on a quad lock (looks like a very secure system) connected to an in-steerer USB charger (I can start a ride with an empty battery, which will be fully recharged after 30 kms), running Locus which supports ANT+ sensors (I typically use speed+cadence and sometimes HRM) and is an otherwise very well designed (free) navigation app.