I've tried it in Ohio. I can't see the difference, since super premium is 93 octane in any brands in the areas where I travel. Last year I filled up with the Sunoco 94 in Cleveland, and refilled with the same, half way home. I got my usual 26 MPG traveling all intertate at 70 - 80 MPH on cruise for 675 miles. (except, of course for pit stops)
What I really can't undersand it these guys driving around on 89 octane gas, when the car's manual calls for premium. I think that's where some are getting their carbon buildup, knocking, gumming, etc.