A wanton disregard of the butterfly effect (which a school of AH.commers, myself included, feels is paramount; you won't have the same people born after the POD, save perhaps name).
Speaking as someone of the "butterflies aren't the problem, jalapenos in your PB&J are." school...'tis still a problem.
Long lasting slavery and more slave states, empire-wank...those are the two main things that bother me far more than zombie FDR.