Sorry but I have to defend Optimax, the report you refer to was a test using one gallon of Optimax, then using one gallon of supermarket fuel. Hardly scientific or representative of normal conditions.
Having made a statement by owning and running a Lexus, I would recommend you stick with the better fuels. Shell, BP, Texaco etc. supermarket brands are refined by the big companies, but they don't get the additives.