I don't really have an opinion, as I'm not familiar enough with the math and most of the people who are interested in explaining the math seem to be zealots who would say anything to support their particular view. I also think the debate is muddied because everyone has a different definition of "suburb" and the math is not the same depending on which version you're thinking of. There are also other factors to consider, like dense areas not having to pay for raising and educating the people who move into them but collecting their tax revenue.