The good thing about that fuel additive is that you really cannot use too much as it is a byproduct of gasoline anyway. I have always used Seafoam in my boats but have found some relatively new stuff. Been on the market for a couple years or so I guess, called Formula X2.
It is supposed to do everything the other fuel additives do but it also allows any moisture that ethanol may bring, and completely mix with the fuel and burn out of the engine. To my knowledge I have not had any moisture problems, but I figure it is better to be safe since I do live in a very humid environment.