Assuming same steel, same heat-treatment, same edge angle, and same edge finish, the edge retention should be the same. The flat grind generally offers less cutting resistence on stiff materials because the flats of the blade don't have to wedge the material apart as quickly. On soft materials, the greater surface area of the flat grind's primary bevel can become a liability, creating more drag than a flat saber grind which wedges the material apart quickly before going to the flat sides, which may not even touch the material being cut.
I don't believe in safe queens, only in pre-need replacements.