A single node 4 CPU SE should scale even better than 2 node x 2 CPU SE RAC so using SE RAC for scalability is luxury and company doing so has way too much money. Availability? Well, besides Oracle licensing, HA environment requires fair amount of investment if it's really HA and not just "reported" HA because of RAC. If company with HA requirements can't justify cost of EE and RAC option in addition to the infrastructure behind then they really have to think about changing their business model and/or IT architecture.
…well, a modern two way can move about 350MB/s with PQO doing goodies like index creation and statistics updating and only about 40-60MB/s without it…and that has nothing to do with partitioning. With a decent SAN, a 2 node cluster of 2 CPU servers can scale that as well. I can see how a 2 user system could do without PQO, but then a 2 user system should not be capitalized by a company opting instead for hosted I should think.
-- Best regards, Alex Gorbachev The Pythian Group Sr. Oracle DBA http://www.pythian.com/blogs/author/alex/ http://blog.oracloid.com -- http://www.freelists.org/webpage/oracle-l