Yes, the economizer is one tune and that's it. However, I will say this, getting into this tuning stuff should not be done for mpg reasons. You may not get any improvements whatsoever, irregardless of what people on here post about or what your friends say. MPG calculations are very much individual, to the point of if you have a school book in your truck and your friend or someone else doesn't, they may or may not get better mileage then you(little bit of an out there example, but that's how nitty gritty it can get). The best mod for mileage that you can do is train your right foot to be better with the go peddle.
I am assuming, of course, that economy is at the forefront of your mind since your looking at the economizer, in my mind there wouldn't be another reason to look at that tuner especially since it's only one tune.
If you get a tuner and you get a bump in mileage great, that's icing on the cake, but don't do this with the main goal being economy. More often then not you'll be disappointed.