Just bought a Napoleon BBQ with porcelain coated cast iron grates. The manual recommends using a brass wire brush for scrubbing them, however, most stores have moved to selling only stainless steel brushes. I went to a speciality BBQ store who is an authorized reseller of Napoleon. They told me that the stainless steel brushes work just fine as long as you don't use the scraper end.
What are your experiences with different grates and brushes?