I know multipule domains is usually a bad thing. I had a website that has in a way to core businesses. One that has volume over profit and another that has profit over volume. obviously the business stream that has more volume is SEOed allot better and the other one is hurting. I am having allot of problems builing SEO around that core business stream. My thought was to "separate" the content of the site over two domains. put all info regarding business model A in the original domain and 301 redirect all business modle B into a different domain and vise versa Would this be tragic to google seo?
I don't think so you can use multiple domain but use 301 redirect to your main domain, this can help to avoid Google check for duplicate content.
The issue with the 301 redirect is the link equity fades over time. you may want to consider keeping both sides up and just maintaining the links back and forth.