My advice is to use Oracle x86 virtualization. I know absolutely no one that is overly happy with Solaris virtualization. It needs to time to mature. I would personally convert to Oracle Linux and Oracle VM x86. 18.104.22.168 is pretty stable with the latest PSU patch. I would probably go with 22.214.171.124 PSU 9 or 126.96.36.199 on the DB side.
Either way, the fact you're doubling the cores and the RAM... means whatever you run, you're going to see much improvement. PVM Oracle Linux guest run Oracle DB very well. In fact, on low to medium work loads. It actually is faster. Under heavy loads at max SGA use, nothing is going to beat physical. Oracle VM is the best virtualization for Oracle DBs.
Check out this document from Oracle