I think that part of the reason that camber has not been identified as a really important airfoil characteristic to optimize for pylon planes is that zero camber is so close to the ideal value. If none of the symmetric airfoils were able to operate in the drag bucket during turns, then camber would be more of a hot button. If you look at the specially designed pylon airfoils, I think you would find that they all have small, but non-zero, camber.

banktoturn