Jack Cox (former editor of Sport Aviation, and current editor of Sportsman Pilot) had some very astute observations about this topic in the Spring 2007 edition of Sportsman Pilot.
Jack believes that the LSA weight standard should be logically based on wing loading, rather than gross weight. As Jack observes, much of the way an airplane performs is based on wing loading, not gross weight. An airplane with high wing loading will have a higher sink rate, as opposed to one with a lighter wing loading which will "float like a butterfly."
Jack noted that some of the approved LSA's have a much higher wing loading than C150-152, for example, one of the most popular LSA's is the Flight Design CTSW which has a wing loading of 12.3 lbs per sq ft, compared to the C150 which has 10.3 lbs per sq ft.
There is a lot of illogical stuff in the LSA standards, for example An Aeronca 11AC Chief is LSA approved, but the 11BC Chief is not, because it is 30 lbs heavier, but both airplanes perform nearly identically. If wing loading had been the criteria instead of gross weight this would not likely be an issue (llAC has 7.3 lb loading, 11BC 7.7lb loading.)
Jack identifies eight airplanes that meet all of the LSA criteria except the gross weight limitation, including the C150, if wing loading were used instead of gross weight, all of them would qualify.
It's an interesting observation, and a good one I think.
