At high elevation sleds will run richer then sea level so odds are it will balance out in the end.
You are correct. But im not so sure about altitude being that much of a difference because all of our sleds compensate for that i believe. So saying its safer is kind of a gray area. And I would bet money that if it came down to a warrenty issue polaris would check your fuel and check the computer to see what resistor you was running on.
To educate a little bit: Why ethanol even exists in our fuel today is because each state has to meet a certain amount of credits for the clean air act.(or something like that.) So instead of investing fully on E-85 fuel and E-85 engines, local governments decided to put a certain amount of ethanol into our every day fuel to gain their credits. Thus why each state is different on weather or not they have ethanol or non-ethonol fuel.
Now how it works is distributors get the fuel from the refineries and they use the alcohol(ethanol) to rasie the AKI of the fuel. (octane rating) Why this is a problem is because alcohol is very attracted to water. When the two combine they mix very well. Now remember back to when I said they use the alcohol to raise the octane. When water is introduced something called phase seperation happens. Basically all the watery alchol mix is now at the bottom of the tank to be left unburnable and the rest is fuel that just got reduced down 3 or more octane points.
Remember back in the days when you would add some heat to the gas tank to help with the water issues? Well if your burning ethanol fuel then that is a no no. Adding more alcohol to the works is only going to reduce the amount of burnable fuel in your tank.
Thats when we move into sta bil. If your using ethonol fuel I would recommend using sta bil or something equivalent. Why? Well sta bil in no way increases your octane. What sta bil does is increase the btu's of the watery alcohol fuel mix you have to aid the engine in a complete burn. Basically it will run better. There isnt a set additive that works 100% because if there was im sure would here about it alot more. Some additives help in one spot but then take away from another.
Now I could go on for hours about this and the whole ethanol debate goes deep into political nonsence. If you want pm me and ill give you my number if you want to go deeper. What im trying to say is alcohol in our gas engines is bad. We all need to start fighting ethanol in our fuels because state governments are trying to increase the allowed 10% to 15-20% in some states.
Hope this helps