RE: nylon bolts for ultimate lower wing?
If you look at the "ultimate Build thread" you can see where the stress on the lower wings pulls on those lower mounts. The Nylon bolts I think would cause more damage to the plane allowing things to "break away". I flipped my plane 3 times and did only a little damage to the mount. If the wing where to seperate from the mount it would have easily been ruined or tor up something else.