You did explain what you meant by a flat Tax, but please say a flat Tax RATE. Many people are so stupid about math that they can be convinced that a flat tax means that they and Bill Gates will pay the same amount of taxes. It is time to teach people the difference between a tax rate and a tax which means tax revenue.
I much prefer a flat sales tax rate and the total and permanent elimination of any and all income taxes. Nobody should have to reveal their income to the government.