I've been working in Tableau Server for 3 years and have my certification. I recently came back from the 5-day (2-day+3-day) Server Architecture/Administration Training. I've worked with the Tableau Server 9 alpha and beta products and felt comfortable using Tableau 9. However the class was worth while for me and I learned a few new things. I have better insight how Tableau Server 9 architecture works. If you read through the Admin guides you should be fine to support your environment, but I don't think anyone can answer "Is it worth it" for you.