Silly me, I've been getting 10% ethanol gas, or ADDING it if the gas doesn't have it. Consider:
1) You're running the 'water bottle' test the wrong way. Fill the bottle with gas and add a teaspoon of water. This simulates what happens as your saw cycles hot/cold/hot (or sits unused for a while) and moisture from the air gets in the tank. If the gas has alcohol, the water is held in suspension where it can be burned harmlessly in the engine. If the gas has no alcohol, the water goes straight to the bottom of the bottle and sits there. This equals a rusty gas tank or a dead engine depending on when the slug of water gets sucked into the carb.
2) Ethanol destroys varnish. If you don't believe me, pour some alcohol on a nice piece of finished woodwork! A little ethanol helps keep varnish from building up in the carb...especially in tools which sit for a while. This past winter we had a slug of 'real gas' in a generator at work. After several months sitting I tried to start it, but no luck...it wouldn't run. Tore down the carb and it was loaded with varnish. I decided to try the much talked about 'Chevron Techron', but it wouldn't touch the stuff even after soaking a couple of hours. I grabbed a bottle of ethanol out of the chemical cabinet and it literally dissolved the varnish as I was pouring it on the parts.
3) If the fuel is breaking down in storage, it's the gasoline not the ethanol. I have a few bottles of whiskey on the shelf well into their second decade of life and they are as good or better than when they started out. I'd like to see anyone burn 20 year old gasoline!
3) Likewise, I have some cheap booze on the shelf for when friends come over and I just want to get rid of them. It's in clear plastic bottles which are perfectly fine even after years of contact with 40+% ethanol. If a low end / rot-gut booze manufacturer can make a disposable plastic bottle which is fine in 40% ethanol, surely any company worth 2 cents can make a saw and engine parts to withstand 10%.
4) "There is no good reason for having ethanol in gasoline" - I certainly agree with that! With ethanol being well over 100 octane, they shouldn't blend it with 87, 89 or even 91 'premium' crapolene. It should be saved for uses where high power is needed in a light weight package and/or people want a clean burning high performance fuel tolerant of a wide range of heat/moisture conditions.