As the maintainer of the Solaris Package Archive http://www.ibiblio.org/pub/packages/solaris/sparc/ I've been blessed to use every single Solaris version on SPARC and x86. I find that it's harder to get businesses to run Solaris as 1) Oracle pricing sucks and 2) the free versions don't have a support infrastructure worth a damn so managers can't justify the risk.
It's a shame to see OmniOS disappear, I can't say I've run it myself, I don't have the infrastructure to set up the labs.
BTW if anyone wants to donate machine access I then can continue to build newer packages etc. I'm serious. Currently my hardware access is limited and not stable enough to warrant investing the time to set up 10 and 11 LDOMs/Zones and 8 and 9 guest Zones etc. ta++