I got the Craycort grate 14 months ago. I am very happy with it, but I certainly recognize that it is not for everyone.
I have had no trouble keeping my grate seasoned - it has built up a nice glossy black finish, and now has what is essentially a non-stick surface. Rust simply has never been an issue for me. However, my grate has not reached this happy stage without a considerable amount of effort and care. Whatever this beast may be, it is absolutely NOT convenient.
First, I do not keep my grate outside on the kettle. It stays inside my house, in the box in which it was shipped (which I need to replace). I only bring it out when I am cooking steaks or other chops. Immediately before every single use, I coat the cooking surface with a thin coat of Crisco. An hour or so after every single use (while the grate is still warm/hot), I knock off any debris with one of those black rectangular plastic grill scrubbies, lay down another thin coat of Crisco, and back into its box it goes, to stay inside until the next time I cook steaks/chops.
I have never once departed from this routine, and my effort has been rewarded.
I recognize that few people are willing/able to go to these lengths, given the size and weight of the Craycort grate, as well as some amount of "mess factor" in lugging it inside for storage after every single cook. Those who are willing to invest this level of care would be well advised to go the cast-iron route, as it turns a kettle into an entirely different grill.
Grill-jockeys who value convenience would probably be better served by the SS hinged grate, or perhaps the Weber Gourmet System, if they are willing to invest a little more care into keeping the CI insert seasoned.
