I know most has been said but I would think bevel angle might alter the longevity of the edge as well as the steel and the coarsness/density of the hair, and the ability of the user to maintain the edge. Softer steel is easier to hone vs. Stainless which is very hard material but holds a great edge once shave ready. The tip of the edge of a bevel is probably tapered down to only a few atoms thick anyways if you could view it under a powerful enough microscope, the hairs themselves obviously will flex the edge in spots and maintenance is key to keeping them aligned.