Wear on edging blades is an annoyance we all try to cope with. Generally, increasing the amount of steel that has to be worn away, increases the life of the blade. So, a straight blade would probably not last nearly as long as a disk. A larger diameter disk has a longer perimeter and more steel, so it theoretically should last longer so long as you have enough height adjustment range to cope with it. I'm not very comfortable with bushing the center though - if a disk-type blade comes off at full speed, it could easily hurt people very seriously. That is the downside of disks versus strip blades, and larger blades in general: they contain more kinetic energy and therefore have more potential to cause harm.
