I use the Stok cast iron grate on my Performer. I would prefer the Weber gourmet BBQ system, but I got the Stok at wholesale through the place where I work.
I use the cast iron grate for everything but the long cooks where I know I will have to add charcoal. It is great for direct cooking, but since it doesn't have the lift up side grates, I use the original wire grates for the long cooks.
I recently picked up a cast iron grate set on clearance for my Jumbo Joe, but have yet to use it.