I've been using the craycort grates since shortly after they released. I can say that I have been very happy with them. I will say that I kept the fold up stock performer grate for easy "reloading" while cooking full birds, or other big hunks of meat.
Funny story, right before Christmas a couple of years ago I was talking with my father and I told him I was sick of people buying me grilling accessories (call me shallow or ungrateful, but I honestly would rather see people donate the money to some charity that they see fit). Low and behold he bought me another craycort grate that year. I felt terrible because I was very vague on giving gift ideas for anything, and I know he really thought he got me something I would be excited about. In my opinion he has done so much for me (he was a fantastic father and still is) that he really shouldn't be spending any considerable amount of money on gifts my way these days. Well I ended up giving that extra grate to a friend that I had traded my old 22.5" OTS for a nice futon. Well my friend didn't feel OK with me just giving him the grate and bought me the griddle and vegetable basket inserts for the craycort. Worked out great.
The best part of the whole deal is my Dad is always anxious to have me cook food on the grill whenever he makes it up to where I'm at.
Sorry about the OT story.
The other reason I like the cast iron grates is the heat they hold. I usually cook stuff with all the heat on one side of the grill. As the cook progresses I'll spin the grate 180 degrees and move the food back over to the nice and hot grates. Grilling is an art IMO. I come on these forums and compile and use ideas that others have posted as a reference as to how I'll cook my food. I've found my way to cook food that tastes great to everyone that I've entertained, at least they say it anyhow. The most important tool in my arsenal is a nice digital thermometer. I've always been a "read the manual guy," and maybe if the food doesn't taste the best ever to me, at least it will be safe to eat.