Love what you are doing with the new firmware!!
Is it possible that the UCM05 / standard units Can be upgraded via the comfort bus as well as direct from PC?
I have a unit which is connected not to a PC, so It does mean have to play around with the wiring, which your new system does away with!!
The UCM05 (I presume this is one with the RS232 Interface) can only be upgraded by direct connection toa PC. A module can only be upgraded by 1 method, direct or by Bus and cannot support both methods of upgrade
I think you should be able to bring a laptop to whereever the UCM is to do the upgrade