The fear of ethanol is based upon chemistry (which won't change with time).
Actually it has and will continue to do so. There is loads of research being undertaken by the oil companies and bodies such as ASTM, EI etc concerning the chemistry of ethanol in fuel which has greatly increased our understanding. Furthermore bodies such as the LAA and EAA are looking into the aviation aspects of the fuel. Regulations and recommendations concerning use of Mogas in aircraft are changing, albeit slowly. Rod1 commented above that his aircraft has been cleared to run on E5 which is a perfect illustration of this point.
Oil companies fight the bad chemical behavior of such mixed substances by restricting storage of fuel to 90 days after tap and adding additives, of which some fetch water and ethanol, thus rendering our basic ethanol tests virtually useless -> if you don't see a separation on the water test, it does not necessarily tell you there is no ethanol! Whether the water and ethanol fetched by additives is doing harm to the use in aviation is totally unclear.
That post, with respect, is typical of many on Pprune concerning ethanol, which routinely contain an eclectic mix of facts, myths, half truths, and faulty conclusions therefrom. Water and ethanol fetching additives? There are additives (IPA) that can deal with low level water contamination but those are in fact approved for use in aviation fuels including Avgas 100LL. Thus, the affect is not "totally unclear" Furthermore, its extremely rare to find IPA in Mogas (if you do its unlikely to contain ethanol for reasons I won't bore you with.)
There are no additives that "fetch" ethanol (though if you added enough water to a tank you could remove the ethanol from the fuel though I'd hardly class water as an additive).
The only part I sort of agree with is that a fuel that passes the separation test (note it was not designed as an an ethanol test though it can be an indicator of ethanol) may still contain ethanol. I again take issue with the "totally unknown affects" opinion though.
FWIW, I'm happy to use Mogas with or without ethanol subject to the following:
The aircraft doesn't have ethanol compatibility problems in fuel tank and lines.
The aircraft doesn't suffer from water ingress into the fuel tanks during rain
I'm not intending to fly hot and/or high.
The regulations allow me to do so.
M9 (Investigates fuel quality issues for a living and regularly flies on E5 Mogas)