Our current setup has 4 vCenters 5.5 (Windows), 2 VMs running SSO role on Windows and 1 VM running the WebClient on Windows. We will be upgrading this month (finally) and we're moving to the vCenter appliance. Desired config will be two appliances running PSC / SSO and the four vCenters will be appliances running just vCenter. We have no longer need for a separate web client.
Now the big question: When and how in the upgrade path do I remove the webclient VM? Is that after the last vCenter Server has been upgraded? How do I remove it properly, just a normal uninstall?
I think this is covered in the official product documentation in the upgrade paths that show the distributed topologies, but if memory serves there's nothing you really need to do. After the migration is complete, the web client role will be collapsed into the vCSA housing the vCenter Server function and you can just delete the corresponding VM from 5.5 land.