I have to add...
The on-device adjustments are more user-friendly on the Predator. You can always ESC out if you change your mind. With the Xcal2, if you say you want to load a program on your car, then go into changing some settings, but then decide to back out, there's no backing out. It will flash what you did. It's probably not a big deal to experienced users, but it can get confusing to newbies.
On-device datalogging is nice too. You can watch 5 items on the screen at the same time. If you selected more than 5, you just have to scroll. No need for a laptop.