I dont understand. Is it "an older version"? or is it "a still supported version"? It cant be both.
No security updates anymore and no plans to bring it to the latest rhel/centos, sounds like its been silently abandoned to me.
Its like redhat stops releasing security updates for rhel 6 the minute rhel 7 is out.
plesk 12.0.x has been declared stable by marketing but that doesnt mean it really is. SSL sites disapearing with every update, the zillion problems updating, etc... etc... one only has to read the problems forum to see its far from true production ready.
regards
Jan