When I tried a hoop, I used 1/8 X 3/4 Aluminum bar stock, that is what I decided was too flexy. I can see where steel gives you the stiffness you need.

The brace on mine is steel, not because I thought it was better but because it was the nearest thing to hand at the moment.

Regardless of our method to solve a problem, I think it clear that the Axiom rack as sold is not an adequate rack by itself. It needs some reinforcement. I have better racks that I use on other bikes, but unfortunately they fit poorly on that particular bike.

There are only two things I like about the Axiom rack compared to my other racks. (1) The panniers are mounted a couple inches higher than they are on other racks. On my expedition bike where I am often off road, I like having the panniers up higher. And (2) that bike I transport in an S&S case, the Axiom rack when removed from the bike is easy to pack, as the two halves are pretty thin when packed.