Hurricanes and housing busts have already battered South Florida’s image as an earthly paradise. But Miami’s reputation for dysfunction is on display again this spring as the Obama Administration shifts health-care reform into high gear and a spate of studies slams the Magic City as the poster child for exorbitant medical costs. This week the Milliman Medical Cost Index listed the 2008 average private-provider costs for a Miami family of four $20,282 as the highest among the 14 major U.S.