I have setup a few units to plant corn with the SF1 AutoTrac on both integrated tractors and with the ATU. Some setups had the operators planter and corn head head row numbers matching and some didn't. In all cases the results were acceptable, outstanding when you consider that we were seeing 2 inch or better accuracy out of a system that is supposed to be within 12 inches or so.

With that said, I agree with John's post above - one has to remember that it can take more 'babysitting' (hitting shift trac etc) to get these results from SF1. You do need to check on it from time to time, particulairly during periods of the day when sattelite availabilty is going to be low for your area (sometimes around sunset as mentiond). The operators I worked with had very few issues with drift etc, but your mileage may vary depending on signal availability, strength etc.