boduke:
For leveling and moving dirt from one place to another, the box blade is far and away the better choice. The extra weight cuts into the soil better than a back blade, and the end plates hold the soil in the box until you get to the low spot where you want to dump it. Also, most box blades have teeth (scarifiers) on the front, which can be lowered to rip up the soil so you can level it. The teeth, combined with adjusting the angle of the blade with the top link, allow you to dig deeper, or spread and level the material. Takes some time to learn the techniques, but I think it would be the better choice.
The only advantage the back blade adds is the ability to angle the blade to sidecast the material off the trailing end of the blade. This can be useful for some operations, but the lighter weight of the back blade will not cut into the soil as well when you want to take material off the high spots and deposit it in the low spots. The back blade will tend to follow the existing contours of the land.
Hope this helps. /forums/images/graemlins/laugh.gif