Here's another angle to consider. Touring abroad. Would your smart phone work abroad? How much extra would that cost you?

IMHO the technologies have not quite converged for the touring cyclist. Almost but not quite. At least not at a "cheap" price point. For now, a cheap wired bike computer, a GPS with maps, your iphone, or a throwaway in some foreign land, and maybe even a tablet computer unless you don't mind an internet cafe to work out your next segment.

The problem with smart phones is coverage. You just know that when you need it most, you won't have it. Isn't this way the world works?

Happy touring!!