As I'm sure you know, the objective of balancing a symmetrical wing airplane near the center of pressure is aimed at achieving more neutral handling rather than stability. Anyhow, I work with many very bright individuals, and yet even my simple illustration to determine the C.P. is beyond the scope of what most of them are able to comprehend. That said, what's most important is that those who abide by the rule of thumb of balancing at the wing's thickest point will be safe and achieve handling very close to optimum, and since flight testing is seldom performed before airplanes are released to the market, they will most likely fly better than with the manufacturer's recommended CG.