Sorry if this has been covered before. I see its been mentioned but I couldn't see if a consensus of opinion had been reached.

All the research I've done on the web suggest it's harmful to various components in pre 1986 cars. I would have thought many of the components could be replaced with those constructed from resistant ethanol degrading materials but I would imagine to remanufacture the carb would be very difficult and expensive. I've only seen one petrol additive so far that says it helps combat the affects of ethanol but it can't stop the metal degrading effect.

I hadn't thought much about this until the local petrol pumps here in Normandy have just started marking their pumps E10/95 with warnings against using in pre 2000 manufactured cars. (30% of cars round here are pre 2000)

main problem is the fuel pipe which corrodes and rots causing the pump to draw air under high load ( throttle wide open engine under load)
there has been much made of it dissolving brass( jets) and attacking some alloys but what also seems to be a major problem is the ethanol absorbing in moisture and then when the fuel evaporates in the carb it seems to leave furry crystaline residue which can block jets and interfere with fuel pump etc

if you use it, best to keep using the car and not let it stand for a couple of months.
magnets and curly bits of brake pipe which are popular over there do nothing but lighten your wallet, change the rubber sections on the fuel line for "SAE J30R9" stuff and not worry too much about the brass ( increasing the main jet and using cooler plugs also help with the modern unleaded)