Ethanol is not the devil many people think it is. There's several reasons for it's reputation. When ethanol was first put in gasoline many vehicles, boat motors, and small engines had fuel system components that weren't compatible with ethanol. Also some of the older 2 stroke oils weren't compatible either. Modern engine, and modern 2 stroke oils are now compatible.
The other problem with ethanol. It's hygroscopic. It readily absorbs moisture. If a boat, vehicle, or small engine sits a bunch I recommend using fuel stabilizer as well as ethanol free gasoline. If you're going to burn the contents of the tank is a month or so don't worry about it. Regardless of fuel type used it's best to keep the tank full. IE, if you've got a 30 gallon tank, and you normally use 30 gallons a month I recommend filling it every week or 2 instead of just once a month. Air space in the tank is one place moisture comes from.
So, the magic part about ethanol. It absorbs moisture. Gas and water don't mix. Let's say you have a 30 gallon tank. It's 1/2 full, and sits for a few weeks in a humid area. It's very likely the tank will sweat. Condensation will form inside the tank. Water is heavier than gas. It will go to the bottom of the tank, where the fuel pickup is. This will cause some problems. However, IF the 1/2 full tank that sits and forms condensation has 10% ethanol it can absorb moisture with no ill effects. The ethanol separation only happens if the volume of water is too much for the ethanol to absorb. Take 15 gallons of ethanol free gas and pour a gallon of water in it. You're going to have problems. Take 15 gallons of E10, pour a gallon of water in it, and you'll never know. (don't actually try this, there's probably already some moisture in it)
I only use 87 octane "regular" gas in my 4 stroke. I checked the ethanol content a couple weeks ago and it was only 4%. E10 "can" have "up to" 10% ethanol, but it isn't required to have any. (I have access to a meter to check ethanol content)
The only thing I own that I use ethanol free gas in is my generator. It sits, sometimes for years. I use ethanol free gas, and stabil. I start it once a month, but only for a few minutes.
I'm not a marine technician. I'm an ASE Certified Master Automotive technician, and a General Motors World Class tech with 41 years experience. I've also burned thousands of gallons of methanol (kinda like ethanol X10) in race cars.