I feel better knowing that my cycling computer and phone are separate because you never know what is going to happen. I stash the iphone in a seat bag while the Garmin 500 tracks all important things. No need to worry about the phone dying, and in the unfortunate event of a crash, I know my phone isn't too vulnerable.

It is annoying to stop and access the wedge to find out where I am if lost, but its a small price to pay for a little sense of security.