I don't want to come across as if I know this as a fact personally, but some will say that ethanol-fortified fuel (E10), which is 95% of all gas sold @ stations across the country and is all that is available in some states, may cause problems during storage, i.e. absorb water, and can cause an engine not to start when one tries to run it the next season. I don't know technically what happens of if this is just a myth, but it's purported to be a pretty common phenomenon for small engines; not sure about on-road vehicles, but it's enough of a commonly-held belief where I live to make me take precautions with regards to E10 gas and storing gas-powered equipment of any type.
I buy pure gas and fill up the tank and add stabilizer for my lawn mower and would probably do the same thing for my CTX if I were going to store it. In fact, I buy pure gas all the time for both my lawn mower and my bike just for the added fuel efficiency and to protest the fact that the gov't is trying to force us to use ethanol. Not to get too political, but I want to make it plain that I'm not against renewable fuels. I've used biodiesel blends in my diesel car always with great results, but to me, ethanol policy is not smart, only because it has such low energy density compared to petroleum-based fuels, and I feel like we should have a choice in the market, which has been stifled by a renewable fuel standard that requires so many billions of gallons of ethanol blended into our fuel stocks.
If pure gas is available in your area, it's usually about $.15-$.20 higher, because it is so hard for retailers to get and is considered a boutique fuel, and the added fuel efficiency won't make up for the price difference, but it does equalize it some. At $3 a gallon, you can get around 3% better mpg, and if you're paying $.20 more for pure gas, you're really only paying about $.11 more after adding in the mpg gain.
From what I understand, however, drivers in some states don't have the option of pure gasoline due to the formulation requirements. The following link is a pretty complete and updated list of pure gas retail locations throughout the U.S. Canada if anyone is interested.
Ethanol-free gas stations in the U.S. and Canada