can't you also stream Sirius/XM with an app from your iPhone as well... ?
i have yet to be able to justify shelling out major dosh for a GPS. never used my iPhone on my bike but there may come a time... i use it in the car often, but only the *GPS* that comes with the phone. 50.00 for a real GPS app seems FAR better than 250.00- 900.00 for a GPS that will eventually crap out on you.
You think the iphone won't crap out ?