Quick Story (yeah...they always start out "quick"): I had a Yamaha 4 Stroke waverunner prior to my Triumph. When they switched to E-10, I was unaware and later read that your first tank of the new gas should be as empty as it can be prior to filling up because the fuels do not mix well. Also, I was unaware at the time, but my fuel cap did not have a rubber seal on it (I bought this new). Soon after the fuel switch, my ski became sluggish and I spent the next 3 years trying to get it fixed...2 different dealers tried to fix it. After $3k...they finally replaced the injectors and it solved the problem. I sold it.
As it turned out, because of the bad seal on the cap and the water friendly properties of the E-10 fuel, the fuel was absorbing water from the moist shore air.
Moral of the story: I always ensure a good seal on the cap and will blame the alcohol for any future engine "sluggishness" first.
I also do not buy my fuel on the water since they are all e-10, even though my boat is moored. I had a 14 Gal portable tank on wheels that I use. It has a hose and nozzel.
http://www2.northerntool.com/product-1/200325161.htm