I am surprised that this question was not reopened. (How do Tax Brackets Work; Do they Yield Significantly Different Results than a Continuous Curve?)
The question was edited so it was no longer a political question, and although every question here has an economics component, this is not principally an economics question, but a question about how a different method of graduating income taxes would affect taxpayers.
I am a newcomer to this site, and do not yet understand your tribal mores, and would appreciate an explanation of why this Q is not on topic. If, for example, the Q had asked if there was any evidence of how the steps in tax rate affected taxpayer behavior (e.g., is there a tendency to pass on working longer hours if it puts you into a higher bracket), would such a Q be on topic?