Basically, think of the kill box as a far less expensive nugg. The archer and Orion are the same shape but different materials—the Orion is slightly stiffer, more responsive and has a faster base than the archer (triax, sintered), and the archer is flexible and durable (bias, extruded).
Hope that helps!
And yes—a limited number are for sale now, pre 2013-14!
Where?? And how do the Killbox and the Rounds flexibility compare?