Joe I still have enough "Old School" left in me to be VERY intrigued by that Pro40 Wheel bow as well.......Imagine the thought of that "Old School" butter smooth draw, and speeds upwards of 312fps with a forgiving 7.25" brace height!
I can only speculate at this time, but I would guess they found a way to incorporate a solid wall into the design.
It would sure make a day on the 3D course easy on the back muscles.....even with all those blazing speed numbers for the 2003 bows, this one jumped out at me too.