Preferred Database for BSM 9.20 Implementation

A somewhat hypothetical question, and one I used to be sure I knew the answer too, excepting recent developments from Microsoft concerning SQL server. Here goes...

 

If you were implementing a new BSM 9.20 environment what database would you use? Assume you have APM with EUM data from RUM and BPM, SiteScope, and NNMi for infrastructure data collection; and a future need for Diagnostics, OO integration, and uCMDB integration as well.

 

There will be 12,000 - 15,000 managed nodes (network server) and 200 business applications. Current baseline with 1 year of data shows about 500Gb of space used and you can expect that to double or triple potentially as applications and nodes are added. There will be 80 - 100 concurrent users at peak capacity running reports, monitoring dashboards, etc...

 

Please tell me if you would use Oracle 11g Enterprise (RAC is available) or SQL Server 2008 Enterprise, and the reason(s) why.