Certainly a small percentage increase in fasteners would equate to differences in holding strength between same thicknesses of OSB and plywood.
One big advantage of using plywood is that if your going to take a while building at structure, plywood can be sprayed with a sealer and hold up for a long time with little damage from water. You can spray OSB but it won't do any good and will still buckle at the seams from swelling. This is especially important on floor sheathing as it is often exposed the longest and an irregular floor surface will cause more trouble in the long run than on the walls and roof. IME it's worth the extra cost for plywood on the floor but not on the roof and walls.
The biggest problem I see is that people skimp on fasteners. My Carpentry teacher said 32 nails per sheet. 9 nails on the ends and 7 nails in the field relative to roof sheathing over 2'o/c trusses with sheathing laid perpendicular to truss direction. I've always used vinyl/cement coated 8d nails too. Of course we don't get hurricanes in the midwest.
