I have a theory that only cast iron grates really REALLY do the best job of creating sear marks.
Barry, at first the word ONLY kinda caught me. But as I started thinking about my cookers, almost everyone has cast iron grates - either from new or added later. My Weber Performer came with normal Weber grates - replaced them with the Craycort cast iron grates -
http://www.cast-iron-grate.com/ - The 500X is cast iron as is the Lodge hibachi. My fire pit has cast iron grates as does the chimenea (all added later.) The only cookers without cast iron are - G2G, SRG (although I use a cast iron wok on this from time to time), and PBC - but I don't use the grates, I hang my meat... The flat top isn;t cast iron, but it is 3/4" rolled steel and I have to keep it seasoned...
So, I guess, I am on your side Barry. I know you were talking about the sear in your original post, but at the end of the day, I like cooking on iron. Even my favorite pans are cast iron or mineral steel.
David