Correct - export from one appliance, import to another using the wizard.
I've also upgraded to the latest version of 5.0.0 - 5.0.0.6194 Build 920217 and am still having the same issue.
I believe that I am now on the Postgres database (the migration took nearly a day) but I'm still receiving the same error message about "small_icon"url" when trying to migrate from the old vCenter appliance to the new vCenter appliance.