The image is from here.
Please leave a comment if the chart and text are unclear to you. Before that step, however, the hotlink to a 36 page Sept. 30, 2008 analysis of the competing plans is here. Without studying it there remains a lack of a clear understanding of the assumptions built into the $112,000 crossover point that the image presents - for a family of two, four, how many; earned income w/o credits worked in and presuming short form or long; capital gains as a part of income, and how that affects the crossover; etc.
A family running a small business would clearly continue to have more ways and means to minimize taxes than a person earning only ordinary income (no stock option complications; no business property depreciation; no business entertaining expenses) as their taxable income.
Also the detail of the McCain healthcare plan, and the Obama advertising charge that "employer paid benefits" would for the first time be taxed under McCain's plan might be something analyzed in the 36 page item. It's not something I studied - it's posted with that caveat.
It's a summary chart, and a multipage analysis. The pdf is from this homepage (the hotlink on the summary page, which is inactive in the image).