I don't know, that G-Force team is pretty sharp. They could probably rewrite those pesky laws of physics. Personally, I think all teams need to spend all of their time trying to copy this design
As for the field wall question. I don't know about 2818, but we built up a low cost field wall framed up with 1x4s and covered with hardboard. It works reasonably well and isn't too heavy. The worst problem we ran into was getting the corners to stay together. As for flex, I have seen some competition fields with a lot of flex in the sides (more than there should be). Our design flexes, but it is not too bad.