Batman,

I used the same setup on several trips and had no trouble at all. The only things to mention are that the waterproof cases are anything but waterproof (a clear plastic bag solves that one) and that the Bluetooth was not quick enough to pick up the first one or two words of the guidance. But not an issue really as it was repeated later and you get to fill in the gaps.
A 1 amp USB ran my GPS and kept the phone charged. (HTC and CoPilot live)
The beauty about these Sat Navs is the speed of recalculating routes. Virtually instant. As opposed to the Garmin my wife uses. Painfully slow.

Rob