So far I haven't replaced the gasket. Doesn't seem to affect the performance though I do notice a little convection escaping through the millimeter gap. I'm thinking of making my own instead of throwing $20 towards a new one.
I fried my gasket on my primo oval XL ceramic grill and replaced it with a cotronics gasket. Head over to primo's forum and search gaskets and you'll find a thread and contact to buy them. They are used on army helicopters but work great and it will never fry.