I think the url changed:
http://injectordynamics.com/articles/e85/

This part is 100% correct.
It is a mayor deal.
If you are tuned for ie E70. And happend to get E85 or more, watch what happens to your AFRs n compensations. Not even going into coldstarts n wormup.
A highly tuned car will blow the engine on high gear pull due to leaning out and very advanced timing Ethanol car needs.
Get a Ethanol Content sensor and do studies. You’ll see.

Its not about trims.
Its about fueling at WOT, lambdas has no function there.
Its enough to go from E75 - E85 even less to lean out dangerously.

Are you serious asking this question?

LTFTs will not effect WOT fueling.
Variations in low and midrange fueling will be managed by lambda corrections. Correct. But it will throw off precision in coldstarts and warmup. This will be a problem in cold climate countries, not necceerily in warm once. However,  that is not what i am talking about.
Topend WOT fueling will not be corrected by LTFTs
If you are tuned for maxpower on E70 and you get E85 intank - you will lean out. This is based on 8 years driving E85 winter as summer. And I do have Innovate Ethanol Content sensor in my eyesight. Not tuned into Me7, but for these obvious reasons.
I actually dont know anyone that has inplamanted full flexfuel code into Me7. Maybe you do. This would solve this problem ofc.

Since ME7.1 is not wideband, it (at least) is much more challenging.

I do not need to test anything on ME7.1 and I know what the reality is, I have driven long enough with my flex setup and watched my gauges and fuel corrections for long enough  on a narrowband ME ECU.

You fuel up the car with the slightly different Ethanol content (enough you go to Germany to get E10 instead of E5), you let it drive at mid load for some minutes, your LTFA will adjust and you are all set. If you fuel it up and floor it straight from the gas station, then sure, LTFT won't help you.

You say you lean out going from E75 to E85. For the sake of argument let's assume you tuned for AFR 11.5 at WOT, then it "leans" out to 12.0 AFR. Your LTFT needs to be at 1.03-1.04 to sort this out, I get such trims on a stock car just from the stock tune imperfections, quality of fuel, weather, or blood sugar levels of my neighbor. I can believe there are setups pushed to the edge where dropping this 0.5 AFR is dangerous, it does make a difference, but then if it is  on the edge, then something else will blow your engine sooner or later. If your leaning out is substantially higher for this assumed scenario, then there is something else wrong, not the ethanol content If your LTFT does not adjust after mid load driving, then there is something else wrong, like your trims not working at all.