glenn I have run JD auto steer  for four years now on several tractors and a combine.If it works in your area like it does in mine you will be pleased with the accuracy and repeatability.

There will be malfunctions from time to time which is true for any system you might consider,but 95% of the time SF2 will give you good repeatability over time,and I am not talking minutes or hours. It holds for weeks and months.

If you are running all JD equipment I would highly recommend you go with green star.