My test results follow.
Mileage test: This run includes both city and highway driving with hills and stops and starts. I also run it both directions to take out the effects of the wind.
E85 with the stock tune: 15.9 mpg.
E85 with the Dynotune tune: 19.8 mpg
The timed quarter mile with the E85 tune is 14.3 seconds at 96.8 mph.
E85 costs $2.94 per gallon and 87 octane gas costs $3.85 per gallon in our area.
In my case it is a total no-brainer
to buy the tuner and the E85 tune along with running E85 all the time.