Middle class people spend most of their paychecks-- of necessity. The Bill Gateses of the world save and invest most of what they earn. Therefore, the rich will fare much better under this kind of tax than under the present income tax. To overcome the loss of revenue from the income taxes on the wealthy, the result will be either that the Government will have to drastically cut spending, or that the sales tax rate will wind up being very, very high. As a libertarian, I'd like to see spending drop, but, as a realist, I doubt it would.
So....speaking as a Libertarian, you think it's better for the Government to take our money up front, hold it all year, pay us no interest and then let us have some back at the end if we do our paper work right? That just doesn't make sense to me.
Since you're a realist, you should read the paper and grasp what it is saying which is quite different than your presumptions.