I think there is a common misconseption that running premium fuel will give you better performance than regular. I have read in a few places that the lower the octane fuel the hotter it burns and actually gives you better performance that higher octane fuel. Of course this is in a stock engine with stock compression ratio. If you run higher compression or boost, or advanced timing, then you will have to run premium because of detonation (or preignition). That is also that pinging noise you hear, I had an old Aspen that Pinged terrible. Also, I have never noticed any ill effects running the 10% mixture (we have that at Mohawk/Husky in B.C.) so go for it.

 

These engines have enough compression to take advantage of higher octane fuel but the stock computer programming assumes 87 octane regular so unless you have a different program the computer won't take advantage. All gasoline has the same energy content regardless of octane rating. The difference is the SPEED at with it burns. Lower octane fuel burns faster and is more easily ignited. This is why with low octane gas you have to run less timing advance. Too much advance and the combustion chamber gets hot enough to ignite the low octane fuel before the spark plug does and you get pre-ignition or ping. Higher compression does the same thing. Many modern engines run higher compression to get better mileage while under light load. The wide open throttle parameters use less ignition advance because the designers know they are dealing with low octane fuel.
This is one of the main reasons why a good aftermarket tune meant for 92 of higher octane can give noticeable performance gains.
This is an over simplified explanation but that is basically how it works.

 

A couple states dont offer offer the flex fuel engine, I know NY and CA don't.