Ok, lastly: how old is the firmware in the central? Does it/will it ever get another update?

Another update is very unlikely. The current firmware works fine. The only realistic update I could see happening to it is for supporting direct plug-in of newer portables. But since it's a discontinued product (*), they don't have any reason to do this.

(*) The empeg is discontinued, too, but it receives updates only because it shares a codebase with some of the newer products and they can use us as unwitting beta testers for new code.