The marine issue is the damage to fiberglass tanks...quite expensive to fix if the tank is built in.
I have a number of small engines here in FL. I finally added a fuel shut off to each one. Run the carbs dry, and then siphon the fuel out of the tank before storage. I even bought spare carbs to speed up the repair process when necessary.
The only automotive engine I had sitting for several years was a 440 Chrysler. I did add some Stabil. It always started and ran. Eventually I even sucked out most of the gas, and ran it through my lawn tractor, which oddly enough, has never had a problem.
Alcohol packs less energy than gasoline, and will definitely eat into your mileage. No dispute there. E85 can cause a 30% drop. Some states banned alcohol in summer because of the vapor lock problems.
