Link, that's a pretty cool autopilot system.
Years ago I worked on a high seas research vessel that had one of the first GPS receivers. The Navy loaned it to us to try out. First, it came aboard by crane because it was so heavy and big - at least the size of 3 or 4 refrigerators. It was literally a huge "black box". Then it took a couple of hours for its computers to calculate a fix - which was only one line of position which means that we were on a point somewhere along that 100 mile line. ( I think there was just one satellite in the beginning.) And, by the time we got the fix, we were 3 hours from the point where the fix was taken so it wasn't much of a help except to know where we had been - sort of. I think I did better with my sextant...
So I'm always amazed at the instantaneous fixes, the microscopic size, and the incredible accuracy of today's GPSs. Your unit steers to fractions of an inch which is really amazing.