Lots of "True SS 1911's being made, and have been for some time. It isn't the 300 series SS, so isn't as corrosion resistant as, say, 304 or 316, but plenty good enough. Many match rifle barrels are made of 416.
The first SS 1911 was the AMT Hardball I believe, and I'd love to know what alloy they used. The material looks brighter than 416.
Oops! Missed the RIA connection. I agree, that will be nice. I'm an RIA fan.