Considering a 5 or 6 gallon tank and 93 octane 20 cents higher than regular 87, the most you will pay is $1.20 more for your fillup. Kinda of a no brainer to me.
Around these parts the difference in price between 87 octane and 93 octane is at least 30 cents a gallon. So a $1.50 savings per fill up and an increase in mpg is a no brainer to me. Since I refuel on average 3 times a week the savings are greater.
With those kinds of savings you can replace those spark plugs more often.
Look at it this way, the 93 octane I don't waste, is the more that's left for you guys to purchase. Sounds like a win-win for all concern.