We are running 11.2.4, I have 3 Primaries and one external db running on MS SQL2008. The first primary, which also holds the CA is running from the 11.2 appliance with SLES 10.4 which looks like an unsupported platform for ZCM 11.3, according to the documentation. The other two primaries are both running on SLES 11.1. So, I am trying to figure out the least painful approach to upgrade to ZCM 11.3. My options, as I understand it are:

1. Build a new SLES 11.2 server, install ZCM 11.2 and replace the existing Primary appliance with it. Then either upgrade the other primary OS's or leave as-is and proceed with the ZCM Zone upgrade to 11.3.
2. Replace the first Primary server with the second Primary that is already running a supported version of SLES and upgrade to ZCM 11.3. This would leave two primary servers and the external db server.

We have ~925 Win7 workstations and 2000 users so I do not think we really need 3 Primaries so I am inclined to go with option two. I am planning on changing many of the workstations to Windows 8/8.1 so that is my main motive for wanting to upgrade to 11.3. If I do replace primaries, since the appliance also has the CA are there any "gotchas" or if I follow the documentation is it really going to work without a hitch?