I did some quick math...
50,000 miles / 45 mpg: 1,111 gals.
Premium costs about $.50 more per gallon.
1,111x.50: $556 over 50,000 miles, or $69/year for 8 years (assuming ~6000 miles per season).
So, I guess it isn't too big of a deal ... I just like that I can put regular ol' 87 in my Honda and still get 40-45 mpg.