I've had a little experience with both systems, and I would recommend the Ag leader system. Buy a 3000, and you can use it as your yield monitor, and as a controller for any other precision ag function. Greenstar is only accurate if you run a calibration on it every time there is a significant change in conditions (temperature, humidity, grain moisture). On the Ag leader, you use more than one calibration load, and you are supposed to combine each of these loads under varying conditions (change speed, change cutting width, change crop condition if possible). By doing this, it allows you to compensate for the various conditions that you'll operate under, and you only have to complete the calibration once. Also, if you get halfway through harvest and realize that you have done a calibration, you can go ahead and run your calibration loads and it will correct all of the data that you've already collected. It is next to impossible to do this with Greenstar, and the results aren't very good because you still have to base everything off of a single load.