If I were to go to solaris which is a pure price performance decision it would probabally be regular old closed solaris on SPARC
There is no "regular old closed solaris". Unless you consider Red Hat "regular old closed linux".
There is only one Solaris code base. That is what Sun open sourced. There is some platform specific code (I think about 5% of the code). All code which Sun could release is released as open source. Some, which does not belong to Sun cannot be released.
Sun Solaris is simply a distribution of OpenSolaris, just like Red Hat Enterprise Linux is simply a distribution of Linux.