I would definitely recommend staying away from the OnPar. Spec wise it is fantastic. The execution is severely flawed. My unit locked up constantly and the interface was way too awkward for me. I almost bought a uPro, but decided to hold off for a bit. The SkyCaddy units look nice but I refuse to pay a hefty sum for the overpriced unit and then pay an annual fee. It just doesn't seem like there's a good unit out there that does shot tracking, scorekeeping and hazard distances. I know the uPro is supposed to be adding a scorekeeping function.
When the new iPhone comes out, I plan to upgrade and try a couple of the apps to see how they work. I currently use GolfShot for scorekeeping, but I have an original iPhone with no GPS.