George, I sure can’t say you made a bad choice going with Dave’s grates. I don’t even own a set (although I am a multi-buyer of his flavorizer bars and heat deflectors) yet I brag them up as the best because of his consistent quality craftsmanship. On the other hand, I think those 9mm Weber grates look highly respectable to me, regardless of country of origin. I do believe in trying to support US made products, but I wouldn’t be surprised if even Dave’s grates start with foreign made stainless rods. Maybe not, but in any event I have used Weber stainless rod grates for years that were also slightly magnetic (and not as impressive as these new 9mm ones) and never had any problem with them.
Dave’s are clearly the best choice, and maybe I will finally get a set someday. However, I would also be proud to own a set of those Weber 9mm grates. I think they are one of the notable improvements Weber made from the initial rollout of the Genesis II line.