Since the last post - for GPS purposes I am just using Golfshot GPS. I think that the Callaway uPro (and Skycaddies) are more reliable and instant than the iPhone apps, but I just found myself with the uPro turned off any time I wanted to use it (from going to power saver mode after 30-45 minutes of non-use). If an iPhone app is in the background and the iPhone is back to standby, it only takes moments to bring the GPS back up.
As I said above, it seems as if the uPro and Skycaddies are more spot on - where the iPhone you have to wait a few moments to get a stable reading on distance.
A few weeks back, I went to a scramble at a course I had never been to, in another state. Unless I had preloaded that course with my old Skycaddie or my uPro, I would be SOL. With Golfshot, it found the course for me and downloaded the satellite images when I selected it.
NOw on my home courses, I use a laser almost exclusively (when I even need distance) - that goes against my thoughts before that a GPS is better for mid to high handicappers because you should go for the center of the green - but on my home course, I know the greens well enough so I will go to a section of a green. And the laser is instant and exact.