I never wrote you to upgrade using yum, I just wrote to test a yum upgrade to see if there is another Asterisk 11 update ongoing soon…and, AFAIK, there is…but, up to know, only FreePBX Distro developers know when (and if) this new Asterisk built will be available through a FreePBX Distro update (and nobody know if it will be the 11.10.2-2 or just another one newer than that).
Usually FreePBX Distro Upgrade Scripts take care of updating the FreePBX Distro OS RPM packages and (if it’s necessary) also FreePBX and Asterisk’s various packages (it happens regularly with Asterisk security hotfixes): the use of yum should be avoided, FreePBX Distro Upgrade Scripts should be used once they are available.
Regarding SHMZ OS (6.5) and its relationship with CentOS (6.5)…the answer is little bit complex from my point of view (things changed and are still changing) and, again, only FreePBX Distro Developers could point this question out.