I did not see anything saying he can tune based on estimated ethanol content? Or sending the content to a guage, in fact he said he couldnt output/send content anywhere but this software. Maybe i missed it.
The idea of the flex fuel on the ECU as stock is to allow the ECU to adapt to the increased fuel volumes required to run the car safely.
If you want to have a display of this E content then currently the only way to do this is via an external display. This is something we have done either by a wired or BT to a free to download app.
With regards the increased power E can afford you, there is currently not a way I have found yet that can increase the timing with more E fuel contents. It was only ever there as way to run mixed fuels and as stated above related to fuel Injection. E30 needs about 25% more fuel for stoich.
What you can do though is flash the ECu with say an E30 map which has the extra timing added but this can only be used on this E fuel content. If you then ran E50 a new map would be needed to get more timing.
The flex fuel system is basically a safe method of running E fuel without maxing out the fuel trims or having to have a manual increase in fuel via seperate flash versions.
I think finding a way to increase timing via a E content and rpm map would be possible.