None of my grates are SS. In my big RF, I've been using them for 6 years without issue. After each use, I burn the residual fat, spices, drippings off with my weed burner, wire brush it, then spray with cooking spray. I'm not saying I wouldn't use SS, but the materials to build my cooking grates haven't cost me anything.
Team: Smitty's Real Pit BBQ
Superior SS-3 - Courtesy of Gainesville Jaycees and Superior Smokers
2 Custom Built Reverse Flow Stickburners
Weber 22.5" WSM
Weber 26.75" OTG
Weber Blue 2000 Stainless Performer